How come my cdroms sometimes don't read my cds at all?

[Quad]

for example, right now, both my cdrom and my cdrw won't read any cd i put it. when i click on the drive, it says "enter a cd". usually if i reboot it'll be fine, and both drives will read. any reason why this happens?

thx in advance

 

[neuralfx]

usually, your cdrom is going out, sometimes the laser will read, sometimes it wont, could a few things, you could try cleaning it, if its intermittent, then that might fix it, otherwise i'd look into another cdrom .. good luck .. cleaning it might fix it though ..
-neural