There is a thread under general discussion that brings attention to all and everything concerning the 'my page' and its features. That includes problems with studio aswell.
http://forum.thesims3.com/jforum/posts/list/506334.page
I have reported a simular problem as you in that thread, my problem occure in periods, one week i cant access anything, next week its working, next week again its not etc.
To help narrow down issues about the 'my page' i would advice everyone to adress this issue or related to the above link, this way the technicians can look for similarites of problems vs our accounts etc
In concern about a solution, there are none yet, they are working on it.