If you know the make and model of the CD ROM (you should see that info in Device Manager) I'd try to see if the maker has a web site and then get the latest driver from them. If you can't find a site, go to the computer manufactures site and see if they have a d/l for you specific system. If that doesn't work, if you got CD's with your computer, it might have individual drivers to install. If you don't have that, GOOGLE the device for drivers and Win7. There is always the possibility that Win7 drivers don't exist? You said you recently added Win7 and that could be the root cause of your problem. If you went from x64 to x64 you could be OK if you did an upgrade from Vista to W7. If it was x86 (32 bit) to x64 (64 bit) it could be part of the problem. Anything else you'd have done a clean install probably. So, first thing to do is check is a Vista or W7 driver even exists for the device.
What drive is it BTW?