Just throwing in here with you guys:
AMD Phenom II x4 945 @ 3.0ghz
VisionTek ATI HD4870 @ 512MB of RAM
Gigabyte GA0MA790GP-UD4H Mobo
G.Skill 4GB DDR2 @ 800MHZ RAM
Windows 7 64-Bit Ultimate
Creative X-Fi XtremeGamer PCI-Express
Game/Windows installed on a Western Digital Caviar Blue 640GB 7200RPM drive
Other software (outside of generic Windows processes) that I *have* had running (not all at once, not every program everytime) includesL
Microsoft Security Essentials AV, Impulse, Pidgin, Dropbox, PeerBlock, WhatPulse, Last.fm, Virtual CloneDrive, Subsonic Music Server, Steam, Display Fusion Pro, Easy Tune, and ATI's Catalyst Tray.
Not sure what more is useful (you guys have dozens of debug.err's and half as many save files) but I can reproduce this exact bug in my game every single time. It's extremely frustrating.