Computer Freezes Frequently

[wfg42]

Frequently (at least a couple times a day) my computer screen freezes and emits a terrible scraping if the audio is plugged into speakers until I manually power down. When I reboot, I get the following error in the log:

"The system has rebooted without cleanly shutting down first. This error could be caused if the system stopped responding, crashed, or lost power unexpectedly."

Name: Microsoft-Windows-Kernel-Power
Guide: {331C3B3A-2005-44C2-AC5E-77220C37D6B4}
EventID 41
Version 2
Level 1
Task 63
Opcode 0
Keywords 0x8000000000000002
TimeCreated
[ SystemTime] 2010-01-10T06:39:47.187500000Z
EventRecordID 21377
Correlation
Execution
[ ProcessID] 4
[ ThreadID] 8
Channel System
Computer Desktop-PC
Security
[ UserID] S-1-5-18
EventData
BugcheckCode 0
BugcheckParameter1 0x0
BugcheckParameter2 0x0
BugcheckParameter3 0x0
BugcheckParameter4 0x0
SleepInProgress false
PowerButtonTimestamp 0


I also get the following:
System
Provider
[ Name] EventLog
EventID 6008
[ Qualifiers] 32768
Level 2
Task 0
Keywords 0x80000000000000
TimeCreated
[ SystemTime] 2010-01-10T06:40:11.000000000Z
EventRecordID 21373
Channel System
Computer Desktop-PC
Security
EventData
1:10:52 AM
‎1/‎10/‎2010
7042
DA07010000000A0001000A003400EE02DA07010000000A0006000A003400EE02600900003C000000010000006009000000000000B00400000100000000000000

Binary data:
In Words
0000: 000107DA 000A0000 000A0001 02EE0034
0008: 000107DA 000A0000 000A0006 02EE0034
0010: 00000960 0000003C 00000001 00000960
0018: 00000000 000004B0 00000001 00000000
In Bytes
0000: DA 07 01 00 00 00 0A 00 Ú.......
0008: 01 00 0A 00 34 00 EE 02 ....4.î.
0010: DA 07 01 00 00 00 0A 00 Ú.......
0018: 06 00 0A 00 34 00 EE 02 ....4.î.
0020: 60 09 00 00 3C 00 00 00 `...