You are importing the DVD's VOB files? Or did you simply use the DVD for storage? What are the file types?
What VP version is in use? Upgrade to the latest and see if there's improvement. For licensed users upgrades are free for up to six months from purchase date. After that, VP will continue to fully function but a fee will be required in order to register the newest. Retain your old install file and registration info.
If you can spot files that fail consistently, upload a few for analysis. Use a free server, such as Google Drive or MS OneDrive, get a shared (public) link, copy the link and paste it here or to me in a Private Message via the mail envelope in the top-right corner of this forum.
Using Google Drive, if necessary change "restricted" to "anyone with link can view."