Just tested WB5 on WIN2003 german, latest Servicepacks 6GB Memory.
Can call WBCONFIG, select Skins etc. but by applying and exiting the System was halted.
Same if i'm going throug Controlmanager (Suites, Desktop, Designs etc.)
Stop: c000021a
Windows logon process terminated unexpected
status 0xc0000005 (0x00000000 0x00000000)
System halted
After power off and power on, the new Skin is working fine so fare.