Mudbox 2011 is supported. If you have valid Autodesk Mudbox subscription, you can log mudbox case with Autodesk support. You have few option, under Mudbox help.
1. Click Support center: this will bring you the knowledge base where you can search in our database for existing solution to your problem.
2. Click on Subscription center: this will need user ID and password to log in to get access to log cases directly with Autodesk support. To create your account you can click on Create a Subscription Center account OR http://subscription.autodesk.com/sc/selfregister
Finally you can always use Area discussion http://area.autodesk.com/
Cheers
Anil
Autodesk Product Support
Anil Choudhary
Product Support Specialist
Autodesk, Inc.