If you've already updated to 10.5.5 and don't want to roll back, the good folks at Renewed Vision have found a work-around to get you back in business. The only downside is that you use the ability to play back DVDs (until a permanent fix is issued) through ProPresenter. Here's the post from Greg:
So far we've determined that the DVD component is involved. A temporary solution is to disable the DVD playback.
You can do so by running the following command in the Terminal (copy everything inside the box below):
defaults write com.renewedvision.ProPresenter3 disableDVDFunctions -bool true
Note, that you can't use the preference setting in Pro because it crashes before it is able to save the preferences.
This seems to resolve the problem. If you are experiencing the kernel panic, run the command above in the Terminal and please let us know along with the information requested above.
When you wish, you can turn DVD playback back on directly in ProPresenter, a terminal command is not necessary.
So there you go. As always, remember there's no rush to install Apple's software updates. If your system is working normally, and you aren't having issues that the update is supposed to fix, hold off for a bit. You'll find life a lot easier for you if you stay off the bleeding edge.
[Update] It should also be noted that this seems to only affect MacBook Pros.
That and have a full-bootable backup of your system before you update. Then rolling back is really easy.
Thanks Greg, Brad and others at Renewed Vision for staying on top of this and getting a fix out so quickly. You guys are the best!
Here's the whole thread on the Renewed Vision Support Forums...