Cannot export MPG's

I have Ulead Video Studio and Windvd Creator. Both can capture, edit and save projects. I am also able to export WMV files. But when I try to export Mpeg files (For DVD, DV and online), both pieces of software craps out. It just hangs. I am hoping someone can point me in the righ direction. When my computer was new, both software exported beautifully. After 8 months of use and installing other software, I am thinking this is the culprit. Is there simple download to "refresh" codecs or something. I don't want to reformat my comptuer. Any help would be greatly appreciated!