I'll do all those things, Fed.
In looking at another thread here by someone who was having a similar problem, the suggestion was made to run the system in safe mode to see if the video driver was to blame. Today I downloaded a game that I can't play for more than about two minutes before completely freezing my system, so I just tried running it under safe mode. The game crashed, but this time I received a readble error message. This may be totally unrelated, but I'll give it a shot. Here's the message:
Exception: Access Violation (code 0xc0000005) at address 0049675A in thread 348
Module: Heavy Weapon Deluxe.exe
Logical Address: 0001:0009575A
0012EA2C 0049675A 0001:0009575A Heavy Weapon Deluxe.exe
Params: 000000AF 0012EA54 00000800 0012F2E4
0012F334 004AE9AA 0001:000AD9AA Heavy Weapon Deluxe.exe
Params: 0012F8B0 0012F868 77E93120 0012F8B0
0012F340 004AF11E 0001:000AE11E Heavy Weapon Deluxe.exe
Params: 0012F8B0 C0000005 01F51E90 00000000
0012F868 77E93120 UnhandledExceptionFilter+60
Params: 0012F8B0 00547120 00000000 0012FFB0
0012F884 00506585 0001:00105585 Heavy Weapon Deluxe.exe
Params: 00000000 0012F8B0 0050B8F7 0012F8B8
0012FFC0 004FC388 0001:000FB388 Heavy Weapon Deluxe.exe
Params: 70A71A29 80000002 7FFDF000 F7FEECF0
00120834 77E814C7 GetCurrentDirectoryW+44
Params: 00000000 00000000 00000000 00000000
StackWalk failed (error 0)
EAX:00000049 EBX:00000000 ECX:0012F328 EDX:0AAF0003 ESI:00000000 EDI:000000AF
EIP:0049675A ESP:0012EA00 EBP:0012EA2C
CS:001B SS:0023 DS:0023 ES:0023 FS:003B GS:0000
Flags:00010202
Windows Ver: NT 5.1 Service Pack 1 Build 2600
DDraw Ver: 5.3.0000001.0904
DSound Ver: 5.3.0000001.0904
Product: HeavyWeapon
Version: 1.0
Time Loaded: 00:06:30
Fullscreen: Yes
Primary ThreadId: 348
Times Played: 0
I ran a Google search on Unhandled Exception and Stackwalk Failed, but the explanations were a little vague to me.