I downloaded movies from frostwire,and transferred to Itunes. Movies play fine on Ipod. When I try to watch the movies on computer through Itunes,the sound is fine,image skips. Can anyone help?

Skipping image in video is common bug in iTunes for Windows. I have same problem on both of my computers when I'm trying to view any videos using iTunes, for example music videos which are bought from iTunes Store. Click the video title in iTunes with your right mouse button, choose 'Display file in Windows resource manager' (or something like that), and then manually open the file using Quicktime and it will probably work perfectly.