Re: Windows 7 & GM posting
While I'm using a Mac not a PC, I use Firefox's Auto Form Fill, and it is only supposed to fill things in once you type the first few letters -- very handy for typing in the names of NPCs I use regularly but not often enough to make a full-fledged cast entry for -- but it doesn't just populate a form box upon entering a page. I'm not sure what's going on, but I don't think that's the one causing the problem.
I agree that it's probably the browser, but I'm thinking it's more along the lines of the browser thinking it's a saved password. You could check in your saved passwords to see if there's anything except RPOL's main page in the list.
I'm no expert on computers, tho, so I could be way off target. :p