Lock-up after hundreds of EventID 15

Earlier today when I started up my computer it seemed to work as usual, I only had Firefox open so nothing demanding was running but when I started up Media Player Classic it kept messing up the sound every few seconds and froze from time to time. I opened up the Taskmanager but didn't see much activity there so I opened up the event viewer and it showed several hundred errors with more appearing every few seconds reading (translated from Swedish): "The unit \Device\CdRom0 is not ready for access" and with EventID 15 and Qualifiers 49156. There wasn't even any disc in the drive and when I inserted one it wouldn't read it.

I left the system running but after a few minutes it completely locked up, I couldn't even move the mouse-pointer and it didn't react to Ctrl Alt Delete so after a few minutes I did a hard reboot and I haven't seen the errors again so far however I did have the same error occur a few months back after I first installed Windows.

I don't know if this is something serious or not so I'm posting here to find out if anyone has had anything similar happen and know any possible causes and solutions, with a bit of luck it won't happen again but who knows.

The problem hasn't shown up again in the four or five boots since it happened and I've only found it happening twice before in the log, both times with a few hundred errors. One time exactly two months from this occurance and the other about two weeks before that.

I don't see many warnings, a DNS and Wininit (guard64.dll, from Comodo I think) appear each boot. I do seem to get a VDS Basic Provider error (EventID 1) from time to time including a few minutes before the CDROM error started appearing.