Windows 7: Black screen XPmode Windows 7

Have had XP mode installed & operating for a year on 64 bit Windows 7 pro. Suddenly it will no longer open, firstly saying can't enable integration features. Retrying doesn't work and continue only gives a small black screen. I've tried shut down instead of hibernation as suggested in other threads but no luck.
There have been registry problems in the last week & an update last night didn't appear to have succeeded. Thought I'd fixed the registry problems but did get a warning "C:\windows\prefetch" is corrupt the last time Xpmode was working. Would appreciate any suggestions, thanks