I have recently started getting a popup message on my screen that says Brightness and shows a bar - like a monitor adjustment setting.  The number started high (60's) and has been declining to 36% now.  It pops up on top of anything on my screen and last about 15 seconds, the pc still works but I can't see below it.  Then it disappears.  It seems to pop up about every 3-4 minuntes.  I'm afraid it is part of a virus or hijacker but I'm running a current copy of Norton AV and lots of spyware detection(spybot, winpatrol and adaware).  In winpatrol I did have one file in the startup that I couldn't identify (99191.exe)  I don't know if these are related.

Can you suggest any way to find out what this is and remove it?