I've got on 1 PC 5 copies of WoW, so when I open them one by one I am sometimes getting an error "Could not connect to socket" on one or a few clients and they auto close after that. When I open them in different random order problem has the chance to be solved. Any ideas how to fix that?

My PC is Intel Core Duo 2.4 Ghz, GTX8800 768 mb, 2 gb ram, also I run 2 20 " monitors with horizontal span option enabled.