"You need to restart your computer. Hold down the power button or press the restart button." I couldnt do anything, this message locked my screen and it opened without any reason at all... should i be worried?
That'll be a kernel panic it could have been caused by a few different things, if it's a one off then I don't think you've anything to worry about but if it becomes a regular occurrence that could point to an underlying problem.
See Apple's document on kernel panics. Have a look at the panic.log file and see if you can figure out what caused it. Feel free to post it here if you need help deciphering it.
Kernel panics do happen once in a while. I wouldn't worry about it unless it happens again. Sometimes something funky just happens to cause an isolated one. But multiple ones probably indicate a problem that should be addressed.
Edit: Don't bother reading my post...Jaffa Cake beat me to it.
ok thanx guys. for a moment i felt like im using windows again well ive heard of kernel panics but i never had one. so thats how it is Wildcowboy, actually i did bother to read your post i cant locate any file called "panic.log" though...