Computer rebooting itself

[junji]

first of all, my computer is being screwed up these days.
ive did some system restore and things, but i guess i still have a problem.
because when i scan my computer with AVG anti virus or AD-Aware 2007 the computer reboots itself.
what should i do?

 

[Fragrant Coit]

Sounds like it may be a faulty Hdd or RAM.

Try downloading & running MemTest, and the Diagnostic from the Hard Drive manufacturer.

{Both bootable floppies or CD's}

 

[junji]

Sorry, im not very tech-savy, where do i find this memtest or diagnostic.

 

[bushwhacker]

Here you go, matey.

http://www.memtest86.com/

 

[junji]

ok so it happend again, i was scanning with avg anti-spyware to see if it will work now, and in the middle the computer restarted.
the computer turns on and it says like
it has recorved from a serious system failure or something
and i send the error report and it brought me to this:

Run the Symantec (navex15.sys) tool to fix this problem
This problem was caused by Symantec (navex15.sys). Symantec (navex15.sys) was created by Symantec Corporation.
Solution
To solve this problem, you will need to run the automatic update tool that comes with Symantec (navex15.sys). To learn how to use the tool, go to the Symantec Corporation website.

so i have no idea what the means. can someone help me.