http://bugs.winehq.org/show_bug.cgi?id=25049
--- Comment #4 from awesome ilyakon@gmail.com 2010-11-07 03:23:28 CST --- (In reply to comment #3)
You probably need 'winetricks msxml4' then or both. Start with new .wine on each try.
msxml3 and msxml4 are already installed. If msxml4 component doesn't exist in the system, mathcad doesn't even install and start.