Unlike the DTi6300 etc, the DHD4000 does not use any Linux file system but there are software programs that have been written that can read it. It uses a proprietary file system that goes with the proprietary o/s that is written by the people that make the main chip inside the box.

For the original poster, the fact that your problems with distortion affect the unit when it is playing back as well as when you are watching live TV might be an indication that your problem is power supply related. If you can subsequently watch one of the distorted recorded programs without distortion at a later date would indicate a problem with the hardware not the recording or the reception - does this ever happen? If it does then the PSU capacitors are the most likely cause of the problem - too little voltage being delivered to some component I'd guess. But maybe I am misreading your statement

http://www.hope.co.nz/projects/fusion/

See the section on File Systems on this page.

We can argue about whether a proprietary file system is different from a custom one, but the bottom line is that the file systems on this family of PVRs is indeed a "custom" one, and others (not myself) have done a great deal of work to unpick it in order to write the Fusion Viewer software and the Syphon software which allows us to retrieve files from the DHD4000 onto other PCs.

I guess what a PVR needs is a very simple file system, and for one reason or another it was decided that "standard" file systems (FAT, FAT32, EXT2/3, NTFS) weren't appropriate. It would have saved some people an awful lot of work if they'd just gone for a straight Linux based FS!

Matt