This most likely isn't the only problem you'll be having after "upgrading" to IE 7! If you don't believe that, just Google Internet Explorer 7 problems, which will give you about 191,000,000 hits. Yes, that's 191 million.
Presumably, you've had the problem during more than one discrete Forum session (that is, several times you logged out, closed IE, opened IE, logged back in, and had the problem). If that's the situation and unless you absolutely can't live without IE 7, do the following: