Timeshift problem

[esperado]

My config:
Videocard: Pinnacle 300I (DVB-T)+ Pinnacle PCTV(analog secam), Windows XP-sp2 (last) on two partitions (one just for PVR). Installed Codecs: Pinnacle, Dscaler and ffdshow (desactivated), no errors in com objects and directshow, athlon XP 3200+ 1Gb ram, stable system.
I use Pinnacle Mediacenter, MediaPortal, GBPVR.

The problem:
When viewing direct tv, everything works fine. When i use timeshifting, i got artefacts in images all the 10/20 seconds and drops or noise in sound in the same time. The proc is showing less than 20% usage in the same time, and half of my 1gb memory is free. The folder where i record is on a sata disk and lot of space anough.
Same behavior with MediaPortal, but timeshift work well with Pinnacle mediacenter.

Any idea ?

[gmorse]

How fragmented is the hard drive? Could be just that.

[esperado]

How fragmented is the hard drive? Could be just that.

It is a free empty logical partition i use only for that. Contains only folders for my different pvr. So, i do not think it can be a fragmentation problem.
Anyways, i will "consolidate" the free space to see if any difference. Thanks for your answer.
Christophe.