I had trouble logging on from my work computer for days but deleting the cookies solved the problem--yay! For those non-computer literate ppl, like me, you just go to "tools", "internet options", then "delete cookies".
Girls, it's important to keep this in mind, This forum uses a lot of cookies (that's how it "knows" to tell you that something is new since you last looked - it'll have a little new icon next to it - or if nothing has changed sicne you last looked at a given topic - that's why it'll show up with a check mark next to it). If you don't delete the cookies periodically, the forum will be very slow for you and eventually you'll have trouble logging on. Glitchy, I know (I am trying to figure out if there's a workaround), but please keep this in mind.
If you find one day you can't log in or it's super slow, delete your cookies/clear your cache. In IE, that's under tools > internet options > general > temporary internet files
On my Mac my browser is Safari, and there is an option under one of the menus called "reset Safari." Select that to clear your cookies/temp internet files.