After about a half hour HB dc's and says "not a valid session". Am WTH?
I can't see your log.
How do you expect us to fix your problem when this is the only information you've given us? Attach a log file.
for some reason 4075 no longer binding to my version of wow - like a patch was released or something. sorry no log. just logged on to forums and saw this post and had similar problem