I'm having this problem. On login, I get this string added to the end of the URL:
This began after Firefox went buggy and (for what reason, I do not know) launched in 'Safe Mode'
Well, I removed extensions. Re-installed Firefox. Still goofy.
I believe I am actually logged in. I can view all of the administration pages, but upon clicking "Save", for instance, to post... more redirect to login page.
Any ideas? I searched but did not find this?
Edit: By the way, I tried logging in with IE and got the same results. Seems to be adding spaces, maybe, to some string? Hence the "%2"?