Blu-Ray to WMV-HD issues with 4GB RAM.

I've recently started to convert my Blu-Ray movies to WMV-HD 1080p format. The reason for this is so that I can store all of my Blu-Ray movies on the file server without having to guzzle 30GB per movie. Nothing illegal.Because of all the work I'm doing with video, I recently upgraded from 2GB to 4GB of RAM. Before, when I only had 2 GB of RAM, I was able to convert the BD discs to WMV-HD without any problems.However, once I upgraded to 4GB, I immediately started having problems with the audio/video notstaying in sync. The final WMV-HD product starts off fine, but by the end of the movie, the audio can be as much as a minute behind the video. If I downgrade back to 2GB, I'm able to render perfect WMV-HD files. Memtest isn't showing any errors, and I'm not having any stability issues. I just can't get audio/video to stay in sync when 4GB is installed. Seems really weird to me. Any know of possible solutions to this problem? Thanks. Blu-Ray to WMV-HD issues with 4GB RAM.
Sell the 2GB of ram you bought, and go buy more blu-ray movies! But honestly, I have no idea... Maybe some bottlenecking is occuring? But thats just a stab..Blu-Ray to WMV-HD issues with 4GB RAM.
How could a bottleneck occur at 4GB but not at 2GB?I did benchmark the machine (3DMark and others) with 4GB, and the scores were the same as they were when I had 2GB.
Are you running 32 bit Vista?You may need to upgrade to 64 bit if you want to properly utlise that 4GB of RAM.
[This message was deleted at the request of the original poster]
Yes, I'm using Vista x64.