picture stutters in virtual dub

[Gabriel]

I have been using virtualdub for about three months capturing off my old tapes with fairly good results. Today I captured as usual with custom format 480x480 yuy2 with pic mjpeg compression and the picture repeats a one or two second bit over and over for about 45 sec then goes on and does it again and again. I don't see how this is possible but I've checked several capture files from today and they're all the same. Has this happened to anybody else? How do you fix it?

[Gabriel]

I had thought that I taped this off of cable but see an FBI warning at the end of the tape. This must be a Beta copy of a VHS tape. Macrovision did not affect Beta tapes like it did VHS, do you suppose this is somehow related to that? I tried various custom formats and all did the same thing at the same moment. I tried vd off of tv and it was perfect. If it is macrovision, I still don't understand how it could cause the same couple of seconds to repeat over and over.