Cookies are retained even after explicit delete in IE8
Solution 1:
instead of going to tools -> internet options -> delete... it seems IE has a 'feature' to save data for your frequent websites, so deleting cookies does not always delete cookies.
If you instead go to Tools -> Delete Browsing History -> uncheck 'Preserve Favorites website data' -> then delete cookies, this removes all cookies like it should have in the first place
I don't know why IE8 thought having the Preserve Favorites checkmarked by default was a good idea, but whatever floats there boat! -Jaseowns