I don't think that you need to buy a new camera.It should be ok.I'm telling some ideas but of course it's not a guarantee.
1.What is your Pc?I mean if it's weaker than 1,8 Ghz it may drop too many frames during capture and cannot maintain the different incoming video signals fine.
2.If your computers are ok maybe some mpeg2 codec is not good on your systems.It may be corrupted.Try to get some newer version of this Nero mpeg2 codec.
3.If these fails I could recommend you some better but more complicated editing softwares that can capture good: Pinaccle Liquid 6 or Avid Liquid 7 these softwares can handle mpeg2 and you can burn your videos directly to DVD.Canopus Codec pack is a useful thing too.
4.YOU USE FIREWIRE FOR CAPTURING, DON'T YOU?It has to be used.NO USB!
5.I don't know your camera type but it's only Digital 8?Just because maybe in its menu it's not set to Digital8 but Hi8.
Hopefully you can solve your problem.