cd/ dvd drive opening of own accord

basically my dvd drive door opens and closes several times of its own accord whenever i turn the hardrive on, and randomly through the duration of time i spend using the computer. i wondered if it was perhaps as a result of a virus from an email? i remember about a year ago receiving an email forward which made the drive door open on it's own (and yes i know u should b careful about forwards!)

i can't remember for how long this has been happening, but has anyone else had the same problem, and does anyone know how to fix it? it doesn't stop the drive from working, it is just very irritating!

i have read the 'new users, read this first' post so i apologise if i can't explain my problem very well with computer lingo, but could somebody please just try and help (and i promise i will be very grateful!)

thank you!