Dos window/command prompt keeps popping up. Won't go away

I have an unusual problem. A DOS/command prompt windows keeps flashing up on my desktop and then vanishing before I have a chance to see what it says. It is literaly there and gone before you can do anything about it. This happens every couple of minutes.

I have run an anti-virus and spyware/malware sweep but it didn't pick up anything. I have several suspisions about what could have caused this. Here are the actions that I took in the time before I before I noticed this happening:

I disabled IIS through control panel after mistakenly enabling it while trying to do something else
I installed the latest drivers and CCC version for my single 3870 graphics card but it crashed with a .Net error
I upgraded .Net from 3.0 to 3.5, then uninstalled and reinstalled the above
I aborted an install of Roxio Studio that was triggered by my Dell hardware media encoder

I also moved some video files around and then manually deleted (Through the file explorer) the cache files (etc) from Adobe Premier elements to free up some disc space, shortly after which a dos window popped up saying that it could not find 2 of the files which I had moved/deleted. Though it was too fast for me to see which program had triggered the message. Though this may be a coincidence.

My computer is an XPS420 running Vista home premium SP1, with a 3870 graphics card, a TV, card and the Dell media excelerator installed

Here is my Hijack this log

Logfile of Trend Micro HijackThis v2.0.2
Scan saved at 17:43:56, on 15/02/2009
Platform: Windows Vista SP1 (WinNT 6.00.1905)
MSIE: Internet Explorer v7.00 (7.00.6001.18000)
Boot mode: Normal

Running processes:
C:\Windows\system32\taskeng.exe
C:\Windows\system32\Dwm.exe
C:\Windows\Explorer.EXE
C:\Program Files\Windows Defender\MSASCui.exe
C:\Program Files\Intel\Intel Matrix Storage Manager\IAAnotif.exe
C:\Program Files\Creative\Sound Blaster X-Fi\Volume Panel\VolPanlu.exe
C:\Windows\System32\Ctxfihlp.exe
C:\Program Files\Dell Support Center\bin\sprtcmd.exe
C:\Program Files\ATI Technologies\ATI.ACE\Core-Static\MOM.exe
C:\Windows\ehome\ehtray.exe
C:\Windows\System32\CTxfispi.exe
C:\Windows\ehome\ehmsas.exe
C:\Program Files\Dell\Xcelerator\bin\ehLumaQuarkD.exe
C:\Windows\system32\wbem\unsecapp.exe
C:\Program Files\XPSMiniViewGadget\XPSMiniViewGadget.exe
C:\Program Files\ATI Technologies\ATI.ACE\Core-Static\CCC.exe
C:\Program Files\Avira\AntiVir PersonalEdition Premium\avgnt.exe
C:\Windows\system32\conime.exe
C:\Windows\Explorer.exe
C:\Windows\System32\mobsync.exe
C:\Program Files\Mozilla Thunderbird\thunderbird.exe
C:\Program Files\Mozilla Firefox\firefox.exe
C:\Users\Darkness\Downloads\HiJackThis.exe
C:\Windows\system32\NOTEPAD.EXE

R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Default_Page_URL = http://www.google.co.uk/ig/dell?hl=en&client=dell-usuk&channel=uk&ibd=6081122
R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = http://www.google.co.uk/ig/dell?hl=en&client=dell-usuk&channel=uk&ibd=6081122
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Page_URL = http://www.google.co.uk/ig/dell?hl=en&client=dell-usuk&channel=uk&ibd=6081122
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Search_URL = http://go.microsoft.com/fwlink/?LinkId=54896
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Search Page = http://go.microsoft.com/fwlink/?LinkId=54896
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Start Page = http://go.microsoft.com/fwlink/?LinkId=69157
R0 - HKLM\Software\Microsoft\Internet Explorer\Search,SearchAssistant =
R0 - HKLM\Software\Microsoft\Internet Explorer\Search,CustomizeSearch =
R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Window Title = Internet Explorer provided by Dell
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName =
O1 - Hosts: ::1 localhost
O2 - BHO: AcroIEHelperStub - {18DF081C-E8AD-4283-A596-FA578C2EBDC3} - c:\Program Files\Common Files\Adobe\Acrobat\ActiveX\AcroIEHelperShim.dll
O2 - BHO: SSVHelper Class - {761497BB-D6F0-462C-B6EB-D4DAF1D92D43} - C:\Program Files\Java\jre1.6.0_07\bin\ssv.dll
O2 - BHO: Browser Address Error Redirector - {CA6319C0-31B7-401E-A518-A07C3DB8F777} - C:\Program Files\Dell\BAE\BAE.dll
O4 - HKLM\..\Run: [Windows Defender] %ProgramFiles%\Windows Defender\MSASCui.exe -hide
O4 - HKLM\..\Run: [SunJavaUpdateSched] "C:\Program Files\Java\jre1.6.0_07\bin\jusched.exe"
O4 - HKLM\..\Run: [IAAnotif] "C:\Program Files\Intel\Intel Matrix Storage Manager\Iaanotif.exe"
O4 - HKLM\..\Run: [VolPanel] "C:\Program Files\Creative\Sound Blaster X-Fi\Volume Panel\VolPanlu.exe" /r
O4 - HKLM\..\Run: [CTxfiHlp] CTXFIHLP.EXE
O4 - HKLM\..\Run: [UpdReg] C:\Windows\UpdReg.EXE
O4 - HKLM\..\Run: [dellsupportcenter] "C:\Program Files\Dell Support Center\bin\sprtcmd.exe" /P dellsupportcenter
O4 - HKLM\..\Run: [ATICustomerCare] "C:\Program Files\ATI\ATICustomerCare\ATICustomerCare.exe"
O4 - HKLM\..\Run: [StartCCC] "C:\Program Files\ATI Technologies\ATI.ACE\Core-Static\CLIStart.exe" MSRun
O4 - HKLM\..\Run: [avgnt] "C:\Program Files\Avira\AntiVir PersonalEdition Premium\avgnt.exe" /min
O4 - HKCU\..\Run: [ehTray.exe] C:\Windows\ehome\ehTray.exe
O4 - HKCU\..\Run: [Steam] "c:\program files\valve\steam\steam.exe" -silent
O9 - Extra button: (no name) - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\PROGRA~1\Java\JRE16~1.0_0\bin\ssv.dll
O9 - Extra 'Tools' menuitem: Sun Java Console - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\PROGRA~1\Java\JRE16~1.0_0\bin\ssv.dll
O13 - Gopher Prefix:
O16 - DPF: {49312E18-AA92-4CC2-BB97-55DEA7BCADD6} (WMI Class) - http://support.euro.dell.com/systemprofiler/SysProExe.CAB
O20 - Winlogon Notify: GoToAssist - C:\Program Files\Citrix\GoToAssist\514\G2AWinLogon.dll
O23 - Service: Adobe Active File Monitor V6 (AdobeActiveFileMonitor6.0) - Unknown owner - C:\Program Files\Adobe\Photoshop Elements 6.0\PhotoshopElementsFileAgent.exe
O23 - Service: Avira AntiVir Premium MailGuard (AntiVirMailService) - Avira GmbH - C:\Program Files\Avira\AntiVir PersonalEdition Premium\avmailc.exe
O23 - Service: Avira AntiVir Premium Scheduler (AntiVirScheduler) - Avira GmbH - C:\Program Files\Avira\AntiVir PersonalEdition Premium\sched.exe
O23 - Service: Avira AntiVir Premium Guard (AntiVirService) - Avira GmbH - C:\Program Files\Avira\AntiVir PersonalEdition Premium\avguard.exe
O23 - Service: Avira AntiVir Premium WebGuard (antivirwebservice) - Avira GmbH - C:\Program Files\Avira\AntiVir PersonalEdition Premium\AVWEBGRD.EXE
O23 - Service: Ati External Event Utility - ATI Technologies Inc. - C:\Windows\system32\Ati2evxx.exe
O23 - Service: Avira AntiVir Premium MailGuard helper service (AVEService) - Avira GmbH - C:\Program Files\Avira\AntiVir PersonalEdition Premium\avesvc.exe
O23 - Service: ##Id_String1.6844F930_1628_4223_B5CC_5BB94B879762## (Bonjour Service) - Apple Computer, Inc. - C:\Program Files\Bonjour\mDNSResponder.exe
O23 - Service: Creative ALchemy AL1 Licensing Service - Creative Labs - C:\Program Files\Common Files\Creative Labs Shared\Service\AL1Licensing.exe
O23 - Service: FLEXnet Licensing Service - Macrovision Europe Ltd. - C:\Program Files\Common Files\Macrovision Shared\FLEXnet Publisher\FNPLicensingService.exe
O23 - Service: GoToAssist - Citrix Online, a division of Citrix Systems, Inc. - C:\Program Files\Citrix\GoToAssist\514\g2aservice.exe
O23 - Service: Intel(R) Matrix Storage Event Monitor (IAANTMON) - Intel Corporation - C:\Program Files\Intel\Intel Matrix Storage Manager\Iaantmon.exe
O23 - Service: InstallDriver Table Manager (IDriverT) - Macrovision Corporation - C:\Program Files\Common Files\InstallShield\Driver\1050\Intel 32\IDriverT.exe
O23 - Service: LiveShare P2P Server 10 (RoxLiveShare10) - Sonic Solutions - C:\Program Files\Common Files\Roxio Shared\10.0\SharedCOM\RoxLiveShare10.exe
O23 - Service: RoxMediaDB10 - Sonic Solutions - C:\Program Files\Common Files\Roxio Shared\10.0\SharedCOM\RoxMediaDB10.exe
O23 - Service: Roxio Hard Drive Watcher 10 (RoxWatch10) - Sonic Solutions - C:\Program Files\Common Files\Roxio Shared\10.0\SharedCOM\RoxWatch10.exe
O23 - Service: SessionLauncher - Unknown owner - C:\Users\ADMINI~1\AppData\Local\Temp\DX9\SessionLauncher.exe (file missing)
O23 - Service: SupportSoft Sprocket Service (DellSupportCenter) (sprtsvc_DellSupportCenter) - SupportSoft, Inc. - C:\Program Files\Dell Support Center\bin\sprtsvc.exe
O23 - Service: Steam Client Service - Valve Corporation - C:\Program Files\Common Files\Steam\SteamService.exe
O23 - Service: stllssvr - MicroVision Development, Inc. - C:\Program Files\Common Files\SureThing Shared\stllssvr.exe

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End of file - 7227 bytes

I suspect that this may have something to do with ehmsas.exe, the media scanning element of Windows Media Center, as when you try to manually run this it pops up a dos window for a split second in exactly the same way as my mystery window happens. Though this is just speculation right now.