Grab preview failing

I have been having problems lately with ripping dvd's. I've ripped dvd's before without a hitch, but recently (I probably updated something), dvdrip has been freezing up trying to grab a preview. This is the case for both old and new dvds and for dvdrip 0.98.7 and 0.98.8. Just grabbing a preview gives me this error message:

Job 'Grab preview - title #1' failed with error message:
transcode can't find this frame. Try a lower frame number. Try forcing slow frame grabbing.

I believe that the problem is in dvdrip and not transcode, because it worked fine before. Any help  is greatly appreciated.