killing restart

[shuvit]

hey everyone, my machine has win xp sp2 and ubuntu LTS. the problem is my computer restarts all of a sudden ( and very quick) when running on windows, it happens when i start downloading sth off the internet!

it also happens:

-when i start cmd.exe (command propmt)

-when i click on Start then Shutdown menu, i cannot even select any option, it just restarts very quickly.

-when i start any download (IE and firefox)

another weird thing: i tried to boot into the XP cd and run recovery
console, it asks me to select the operating system, i select and type in the password, and nothing happens! no recovery happens! it just stops again at c:/WINDOWS

please help!




it is not a wireless card driver problem as the internet works fine unless i start downloading sth.