I have been experiencing very similar symptoms on iTunes (Mac OS X). I have seen this once before and it fixed itself somehow. I am still seeking the answer to your question, because it has now happened a second time.
The content is still there sometimes. When I move my mouse around the blank area on the screen, I see the cursor change from the arrow to a pointer. I carefully click (hoping I am not purchasing random things) and I can get into music albums and apps. The view changes and I can see what I clicked on, but when I go back to the previous window in my history (back arrow), I am again seeing an all white screen.
The navigation elements work on the right side of the window. I can go into different things like Game Center, or account information. I just can't browse the main landing pages for music and apps.
I know I do not provide any answers,... I too am seeking help. I just hope my post can help someone smarter than me to connect some more dots to find the answer.