May be your browser. Yours is the third query about display problems I've replied to in as many days & I'll give you the same advice I was given by the support staff here - download Google Chrome. I havn't had any problems since I switched from IE 9 to Chrome.
Otherwise, you can contact Help & Support on this link:-
http://support.chess.com/Tickets/Submit
You could also look at:-
http://support.chess.com/Knowledgebase/Article/View/28/5/i-cant-see-the-board-when-trying-to-play-against-the-computer
The help & support section can be reached from the link at the bottom of each page. Good luck sorting that out.
Greetings.
On my pc, in Tactics Trainer, the Analaysis screen has a very dark background, such that I cannot read the content to the right of the chessboard. The background gets lighter further down, but the text is still difficult to read, because it is still lack on "light black". Any advice? Using IE 8.0 on Windows 7.