When does it beep, what exactly what does the beep sound like (IE 1 long 2 short or ?) and what bios is on the computer (it tells you on the screen when it starts booting)?
First thing to do is stop the automatic reboot so you can read the error screen and post exactly what it says here.
When a critical error occurrs in Windows XP, the system will reboot automatically by default. After the reboot, Windows will then usually show a dialogue with the explanation that the system has recovered from a critical error and will offer to submit this error to Microsoft.
Most of the time these spontaneous reboots are rather unique and are not an immediate cause for alert. However, if the situation is recurring, there is probably something wrong in the system configuration. To get a good idea of what is wrong, it is best to disable the option to automatically restart the system after a failure, but to let it show the error message instead.
To do so, please perform the following steps:
1. Right-click My Computer.
2. Select Properties.
3. In the System Properties, select the tab Advanced.
4 In the box called Startup and Recovery, click Settings.
5 A new window will open:
6. Uncheck the box "Automatically restart" in the group System Failure
7. Confirm the changes in both Windows by clicking OK.
Whenever a critical system failure occurs now, you will see a blue screen with a cryptic description of the error. However, the content of this message might help in finding the appropriate solution to the problem.
Note: Most of the critical errors are due to faulty driver installations or incorrect BIOS settings. Especially in case of misbehaving drivers, the blue screens often list the filename of the driver that caused the crash.
How long has this problem been occurring?
If it is less than three weeks you might be able to use System Restore to reset your system state back to a working condition.
To do so, try to boot to Safe Mode with Command Prompt
(start tapping F8 as soon as you boot the computer), boot to safe mode with command prompt.
Log on to your computer with an administrator account or with an account that has administrator credentials.
Type the following command at a command prompt, and then press ENTER:
Follow the instructions that appear on the screen to restore your computer to an earlier, working state.http://support.microsoft.com/kb/304449/
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