The problem can be the result of incompatibility between a driver and DEP which is a microsoft security technology. Have you installed any drivers, hardware or software lately? If you did please uninstall them and see if the computer stabilizes. If you are not able to identify the source of the problem try to disable DEP. Use the procedure below.
(adapted from microsoft article 886348)
Method 2: Turn off the DEP feature in Windows XP SP2 If you need the functionality of the incompatible driver, you can turn off the DEP feature. To do this, follow these steps:1. Restart your computer.
2. During the restart process, press F8.
Note On a computer that is configured to start multiple operating systems, press F8 when the Startup menu appears.
3. Use the arrow keys to select a Safe Mode option, and then press ENTER.
4. Click Start, click Run, type cmd, and then click OK.
5. At the command prompt, type the following, and then press ENTER:
bootcfg /raw “/noexecute=alwaysoff /fastdetect” /id 1
Note If you have multiple start entries or start options, you may have to manually modify the Boot.ini file for your computer. To do this, follow these steps:a. Click Start, click Run, type sysdm.cpl, and then click OK.
b. On the Advanced tab, under Startup and Recovery, click Settings.
c. In the Startup and Recovery dialog box, click Edit.
d. Change the /noexecute option to the following:
e. On the File menu, click Save, and then click Exit.
f. Click OK two times.
6. Restart your computer.