help ! pc keeps restarting

hi all
i have p3-700 mhz machine with 256 mb ram which keeps restarting at least for 4-5 times every time i boot the machine for last one week.

please help me as this weird thing is happening for the first time.

Hi,

Download CCleaner, installs and runs using their first choice of "cleaner" All options to remove Internet Explorer, Windows Explorer and System (not tick history completion), then uses his option to "register" to clean everything the Windows registry, make backup.

we need more information. any softwares or hardwares installed recently. check this guide for instance: http://forums.techarena.in/guides-tutorials/481151.htm