Stutter when playing AVI

[druid9]

TV-Server Version:
MediaPortal Version: 0.2.3.0 with SVN
MediaPortal Skin: Monochrome
Windows Version: Windows XP SP2
CPU Type: Intel Pentium 4 3.4GHz
HDD:
Memory: 1Gb
Motherboard:
Motherboard Chipset:
Motherboard Bios:
Video Card: NVidia GeForce 6600 GTS
Video Card Driver:
Sound Card: Audigy 2 ZS
Sound Card AC3: coaxial out
Sound Card Driver: kx driver
1. TV Card: None
1. TV Card Type:
1. TV Card Driver:
2. TV Card:
2. TV Card Type:
2. TV Card Driver:
3. TV Card:
3. TV Card Type:
3. TV Card Driver:
4. TV Card:
4. TV Card Type:
4. TV Card Driver:
MPEG2 Video Codec:
MPEG2 Audio Codec:
Satelite/CableTV Provider:
HTPC Case:
Cooling:
Power Supply:
Remote:
TV: Sony klv-v32a10
TV - HTPC Connection: dvi to HDMI


In the last few weeks I have begun to experience stutter when playing back AVI files.

Every minute or two, the video playback will briefly pause then continue on, almost like a dirty CD, or (showing my age), a small scratch in a vinyl LP.

Possible culprits are some sort of load imposed by the audio - it seems to more frequently occur when a loud noise is involved in the audio track (that might also be just my imagination), maybe antivirus scanner?

Video playback is otherwise perfect, and this is just annoying. I did install a 3rd hard drive in the machine recently, and this is where the avi files are stored. Could this be the problem?

Any ideas to help track this one down would be appreciated.