tried logging into your database using windows authorisation, i had this problem a few times using the "admin" account, thats how i got around it.. :S
I use the same versions as your aswell (2008 w/tools + Win7 32bit)
Hope this helps, and if you tried it already and it didnt work, feel free to beat me for this post :P
Also try give this link a quick look
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might be of some help maybe?