I realize you are looking into the issue, but I would like to point out that I am having the same problem. I am taking my recorded tv shows (WTV) and putting them through the WTV (Unprocessed) profile so I can remove the commercials. The resulting file can only do x2 fast forward as stated by chambonito. If I try to go any faster, it just goes back to play. In addition, the rewind does not work at all - it simply pauses for a second, like it is trying to rewind, and then starts playing again. I have gotten the same result with both comskip on and off. I believe I also tried the processed version of the WTV profile and got the same result.
I am also on a windows 7 64 bit machine using the 64 bit version of MCEBuddy (release 11).