Need Help with playback problem

Ok so i took a movie and converted it to mpeg4. When i played the video in Nero showtime the video jumps alot. The jumps are constant. I tried the same video in wmp and it played fine so figured it was nero showtime. However I have a small hd-dvd and blu ray sample file (mkv) and tried playing them in vlc player. One of the videos is fine(blu ray) but the hd-dvd version jumps like it did in Nero. I check my cpu usage and it never goes above 20 percent. Has anyone has this problem? I did a search on the internet and find people have this issue when playing from a dvd drive but not a file on their desktop.


My spec are

Asus P5E wifi
e6600
3 gigs of corsair ram
raptor 150 gig
evga 8600 gts
Vista Home Premium

ps yes my video drivers are up to date