http://bugs.winehq.org/show_bug.cgi?id=30545
--- Comment #3 from Hendrik Knackstedt hendrik.knackstedt@t-online.de 2012-04-29 11:47:15 CDT --- That's it! Thank you so much!
Since s3tc support isn't available in Ubuntu Precise via the official repositories I installed s2tc but this solved this particular problem.
Thanks again.