DVD drives simply use the bog-standard CD-ROM drivers, and are often guaranteed to have no specific drivers issues, so that yellow warnings on DVD drives are usually symptomatic of some other hardware-related issue (although DVD drives that are simply failing can present the same symptoms).
I would perform some basic hardware checks -- ensure that all IDE ribbons/SATA cables are correctly installed, and run some hardware diagnostic tools.
PSU might be failing though, and the DVD drives may be getting an unstable electricity supply.
If the DVD drives are SATA you can try uninstalling/reinstalling your SATA driver (although it may be difficult to do this if your system partition is also on a SATA device).
You can pretty much definitively determine if this is a hardware or software issue, by inserting any bootable DVD into your DVD drives, and rebooting -- having ensured that the DVD drives have boot priority over the hard drives -- although the more extensive hardware test would be to install for example W7 RC onto a separate partition, to see if the same problems occur there. But it's more likely to be bad hardware than Vista
It is possible, but NOT guaranteed, that clean installing Vista might solve this, but in my experience problems of this type are solved by hardware not software fixes.
If you are very unlucky, the issue will be a broken hardware controller on your motherboard
It's more likely PSU than anything else -- but that's just a likelihood, not a certainty