Hi Olaf.  I just did a fresh install and used the WinUAE config file supplied from the download site.  I'm getting the following errors when I try to run OWB:  Could not open version 0 or higher of library "gallium.hidd".  I also get the same message for gallium.library, mesa.library, and sdl.library.  I'm using the latest version of WinUAE on Windows 7 x64.
At Workbench start-up I get a software failure error for RexxMast.  Here's the message:  
Program failed
Task 0x314CB458 - System:C/RessMAst
Error: 0x800000003 - Illegal address access
PC: 0x310B8A86
Wait for disk activity to finish