my cd rom drive is crazy

it keeps randomly opening and closing. i've been told by a few people that it is probably some form of joke virus that is set to only open and close the cd drive. i've ran two full system scans with the most updated stuff i can find with norton antivirus, 3 scans with ad-aware se, and a scan with trojan scan. all have found nothing. i read on the symantec website to try and find a specific file. it's not there. what could be causing this? could it just be the motor? if so, why has it stopped doing it now? it randomly starts up again. i can't understand it. any help would be greatly appreciated! i'm not the most technically minded i'm afraid......

many thanks
nathan

 

whhat are u doing when it does this?

 

it's happened before when i've just been working on a word project, and also when i've been sitting on the net, but the last time it happened the second i turned on my computer.