I have implemented VMM with shadow paging. Works fine but there is a compatibility problem with Windows Aero. When VMM is started with Windows Vista/7 x86 as a guest, the Aero stops to work (windows stop to be transparent). A message "The Desktop Window Manager has encountered a fatal error (0x8898009b)" appears in the event log. Only SMP systems are affected, bug does not happen when guest OS is runned in UP mode. I heard this is the common problem and major VM vendors have had to deal with it. Can you suggest possible reasons of the problem? Thank you!