Whenever I log into the UMD within a minute it redirects me to some site that says I need to upgrade my flash player (which I wouldn't do from any site other than Shockwave's website) it's incredibly irritating and might cause me to not browse the forums anymore. (Admittedly I normally only look at the messy forum anyway!)

Have you got an up to date virus scanner, and have done a recent full scan?

That sounds like an infected browser issue, rather than any issue with the UMD itself. It's never done it to me, and I use the site and forums a lot.