Hello there and welcome,
we’re glad you enjoy our server. We have fixed the Win7 issues. I personally can run L2 for many hours, it’s never crashed for me (on Win7 64bit with a 2 year old graphics card and 4GB of ram). You can try launching L2.exe and then go to task manager (ctrl+shift+escape), find L2.exe in the processes tab and try to set affinity to only 1 core.
I have some more ideas so let me know whether that works or not.