I am not the best one to explain this well, but I will take a shot at it and will try to keep it simple. It sounds like the playback issues you are having are due to fragmentations of the file you recorded. When you record a big file on a microdrive that already has info (video, audio or photos), the info will be saved on different segments of the microdrive. The bigger the file, the more fragmented it will be. For a file that is not too big (usually less than 1h), the playback should be smooth, but for bigger files, it is a lot more difficult to insure a smooth playback as the headers become really big. That is the main reason why most Video files are limited to a size of 2GB on pretty much all PMP and portable digital recorders. Removing the 2h limit of files is not so much of an issue as you can imagine, it is making sure that the bigger files will play smoothly that is a challenge.
The best option would be to record long movies on a card or microdrive fornated prior to the recording. This way you will have no fragmentation and the playback will be smooth. If that is not possible, try to make sure you remove as many files as you can from the microdrives (back them up on your PC) prior to a recording. It will not be as good as formating the drive, since you will still have some fragmentation, but it should help.
I hope that helps- If you want more info on the issue, see the following thread:
http://neurostechnology.com/community/forum/topic.asp?TOPIC_ID=6927FJ
