Computer shutting itself down gracefully

[Gustavus]

Back again with another question. My wife's computer has for the last two days been shutting itself down gracefully sometime during the night. By graceful, I mean the shutdown was normal so that Windows doesn't pop up a box complaining the last shutdown was improperly done as it does when the power is simply turned off. She leaves the computer on overnight to record some streaming audio that occurs while we are asleep and then transfers the recording to an MP3 player to listen to during the day. This has worked flawlessly for many months. Day before yesterday when she got up, the computer was turned off and she naturally accused me of having turned it off before going to bed -- since she hadn't. Same thing happened again last night. The UPS is not connected to the computer with a signaling cable, so the UPS has no capability to turn the machine off -- other than by interrupting the power. That would result in a Windows error box -- which doesn't appear. It appears that some piece of software on the computer has begun activating a normal shutdown sequence sometime during the night. I have no idea of what that could be. Since it is a machine used only for the audio recordings, nothing has been added or removed for a long time. She does allow the Microsoft security updates to be made.

Do any of you have a suggestion of what could be the problem -- or a piece of software I should look for?

Thanks

The machine is running Windows XP with SP2. The audio record program is the latest version of Blaze Audio Power Record. The machine is protected with an up to date NOD32 Security Suite. I ran several anti-malware programs and nothing was found by any of them .

 

[MrControversial]

Is automatic updates enabled on the computer? What are the power settings in the BIOS and in Windows?

 

[L00PY]

Go into Administrative tools and check the event logs. Are things shutting down at the same time every night?

 

[Gustavus]

First, thanks for the replies. I appreciate the help.

MrControversial
Automatic updates are not enabled. The machine is set to notify me when an update is available. I can then look over what is available and select which ones to install. The security updates are up to date but we have not allowed SP3 or the new Outlook Express 7 to be installed.

The power settings in windows are:
Power scheme Home/Office Desk
Turn off monitor after 20 minutes
Turn off HD never
System Standby never
Hibernation not enabled

In the BIOS all wakeups are disabled, Power button 4 second delay, CPU thermal throttling 50% and no remote resume.

I don't see anything here that would account for a shut down on it's own.

LOOPY

The only errors and event logs I see in going back to long before this problem appeared are at bootup. Each time the machine boots up two event logs and two errors are logged.

Here they are in reverse order:
Red X error The following boot-start or system-start driver failed to load kl1

Red X error CRT invalid display type

Information event log The event log was started

Information event log MS windows 5.01 2600 SP2 multiprocessor free

The display is a flat screen not a CRT and the system is a single P4 pentium on an ABIT IS7 motherboard.