http://bugs.winehq.org/show_bug.cgi?id=8421
--- Comment #10 from Dan Kegel dank@kegel.com 2008-10-27 08:21:46 --- It could be because Wine acquired SXS support about then. See http://www.winehq.org/?issue=331#Activation%20Context for some discussion about that feature as it was being prepared. http://www.winehq.org/?announce=0.9.42 shows that this feature was committed in 0.9.42. It changes how comctl32.dll is found.
If you look at how winetricks installs comctl32, you can see that it jumps through some hoops to deal with this; for instance, it removes the side-by-side info for the built-in comctl32 which would otherwise prevent wine from looking in system32 for comctl32.