Aside from the sad fact that you have buggy VIA drivers. 
Nothing else pops out at me, try this stuff first.
Okay let's try some standard things.
1) Rename the AVI folder to AVI_back
2) Set the color depth to 16BIT
3) Turn off everything in the background like E-mail/ICQ/Messenger, Virus protection and everything in the system tray beside the clock.
4) Update your Windows, update your Video card drivers and audio card drivers. Then repeat steps 1-3.
Nothing else pops out at me, try this stuff first.
Okay let's try some standard things.
1) Rename the AVI folder to AVI_back
2) Set the color depth to 16BIT
3) Turn off everything in the background like E-mail/ICQ/Messenger, Virus protection and everything in the system tray beside the clock.
4) Update your Windows, update your Video card drivers and audio card drivers. Then repeat steps 1-3.