I can verify that, with 4Gb of Ram, I am having similar problems with EverQuest 2.
Game may run for hours at a time, and then crash suddenly to desktop, or may just hang right as I try to log in -- don't seem to be able to duplicate situation for when the crash will occur.
I'm running Vista Ultimate x64, so the OS fully supports 4Gb ram. Hopefully this issue is, or will be under investigation by SoE so we can see some fixes in the near future.