This problem is caused by video files encoded in such a way that accurate frame-by-frame navigation ("scrubbing") is not possible with DirectShow.
A fix for this problem is underway. Current version of iPi Studio cannot correctly report this problem. Future versions will be able to report the problem and do video conversion into more suitable format.
The easiest workaround is to convert your video file into uncompressed AVI. You can use VirtualDub (
http://www.virtualdub.org/) to do the conversion.