I will respond. I don't know what the issue is, however, I may offer some suggestions.
The camera itself records to a fat32 file system for compatibilty between macs and pcs and probably other reasons too. All cameras do. Fat32 has a file size limitation. When you are shooting in HD, the length of the clip will be 11:50 plus or minus. Then it starts a new clip.
When you use the software that comes with the camera to import it to your pc, the software stitches those clips together into the original length. If you just look on the memory card, you will see only clips around 11:50. You have to do the import.
Are you using the sony software utility to import?