Do you have an error log from either of those programs? Without more specific information on what is going wrong, we’re mostly guessing here. Since it affects both, I’d say it is a codec problem of some sort or possibly a file association that has changed.
There are better, free, programs for converting avi to dvd if that is what you are trying to do. FAVC is one I recommend. DVDFlick is also reasonably good, and AVStoDVD is a third choice.
If you use FAC, the HC encoder is included and will produce very nice quality results.
Have you tried any of them?