PRECISION WS 490 XP PRO boots, runs fine, then hangs + won't load new tasks, pages, programs.

My WS 490 w/XP Pro SP3 running all current Windows and driver updates has been a workhorse. Love it.

Here is the system:

• Intel Xeon Dual-Core 5160 @3.0Ghz
• 4GB RAM
• Onboard SigmaTel Audio
• Phoenix BIOS Version A08
• Broadcom NetXtreme 57xx Gigabit Controller
• Windows on 70 Gb FUJITSU MAX3073RC SCSI Disk Drive
• Storage is on 1.0 Tb ATA WDC WD1001FALS-0 SCSI Disk Drive
• NVIDIA Quadro FX-3500 - 256 Mb RAM
  
  • Dell E193FP VGA as primary monitor @ 1280x1024
  • Dell P2211H DVI as secondary monitor @1920x1080, 1080p
• Windows and essential drivers on C:\ drive
• All other non-Windows software on D:\Programs directory (problem started prior to this change)
• AVG Free 2013 minimized to Computer Protection, only - all other protection and services disabled.
• Chrome browser (usually)

It mysteriously started hanging last summer and has sent me on a wild goose chase attempting to find the driver/software/hardware problem.

Here's the description of symptoms:

• System boots fine, runs for a while, then with no error messages, will not open new web pages, tasks, or programs.
• Open programs keep running fine, even resource intensive audio and video production software.
• Will not even open Task Manager w/ ctrl+alt+del.
• Will not shut down or restart using Windows Shutdown - must hard re-start using power button.
• Sometimes can go for several days without hanging event occurring.

Here's what I have done, save nuking it and installing XP clean:

• Uninstall/re-install all non-essential software and hardware.
• Uninstalled all AVG components using AVG downloaded uninstaller, deleting all files and folders, and re-installing clean.
• Update all Windows components and all drivers.
• Streamline all services to a "bare-bones" system with networking, USB, and Firewire (for Mackie external audio I/O board)
• Move all non-resident/3rd-party software possible to D:\ directory
• Run all Dell diagnostic tools - no errors found.
• Run all Windows utilities and event logging - no errors found.
• Update NVIDIA driver directly from mfctr to best known XP version.
• Update SAS/RAID driver + console directly to best known XP version (really thought this was the problem, given other forums on the matter)
• Rebuilt boot.ini
• Ran checkdisk /f and /r multiple times
• Use Auslogics Boost Speed to clean + defrag disks regularly, examine and monitor performance tweaks and useful tasks.