Ive got the same Error every day. And the only thing i can imagine is, that Win7 just dont like C3 whatsoever. I get a Critical Error witht eh Message of too less Virtual Memory Space. Yet 50% of my Space is reserved for the Virtual Space. I can keep up 8 Lineage 2 Goddess of Destruction (official server) for 24 houres without a Problem. Blabla L2 wasnt made for more than 1 account blabla. Fact is, i get an Error by just having 1 Char logged in after couple of Minutes on my Desktop and with the L2 client running on Fullscreen in the background.
Alt-tab doesn’t really work, and crashes the client. We don’t know the reason yet, but I have noticed that if some programs are running before you launch L2 (programs such as TeamViewer), you can alt-tab and run more clients etc.