I've only heard of one other user attempting this, and it was with 'Sage 50'. I'm not sure if that's meaningful or even related to your database. It appears that they recently started having problems with the connection failing during foreign key discovery.
You may be able to suppress foreign key discovery or otherwise fine-tune the way Tableau attempts to connect. The following Knowledge Base article discusses how you can customize Tableau's behavior with ODBC connections: http://kb.tableausoftware.com/articles/knowledgebase/customizing-odbc-connections
I also encourage you to contact our excellent support team (firstname.lastname@example.org) so they may work with you to collect more information and look for a possible resolution.
I hope this helps,