I didn't see this posted elsewhere, but I've noticed that in the first nebula mission in the main Freespace 2 campaign, the game locks up and the only way to get out is by rebooting my PC. One thing to note, is that the mission starts off fine, but after a little ways, the game locks up.
I'm not sure if this is caused by a graphics or memory error so I'll give you some quick specs.
Intel Core 2 Duo 2.13 GHz processor
Corsair 2 GB DDR2-RAM
Gigabyte 945-P S3 motherboard
GeForce 8800 GTS 640MB video card
Windows XP Pro 32-bit with latest updates
Maybe it's just a wacky graphics setting, but I'm pretty sure I'm up-to-date with the latest drivers and I'm not experiencing any kind of lag.
D'Oh! Forgot to mention I'm running Freespace 2 Open 3.6.9