Ridiculous Encode Time with Nero Vision 4

I have been using Nero Vision 4 (as part of Nero 7) for a while now without any problems, but a couple days ago I tried to make a video DVD with a couple video files on my computer and the estimated encoding time was insane. According to Nero, it would take about 640 hours to finish the encoding process. In the past I have completed similar projects in about an hour and a half, so I know there must be something wrong. I tried several different video DVD projects and I get the same results every time. I’m just wondering what might cause such a huge leap in encoding time? I’m going to try reinstalling the program to see if that helps, but I’d appreciate any other suggestions you might have.