I am running into the same issue. I am running the same update 24172 on a New MacBook Pro running Mavericks...running Windows 8.1 with the Windows 7 look enabled. I have tried everything...reinstalling Parallels tools, turning on and off Windows 7 look, hot corners, you name it...as soon as I go into Coherence mode...I can't see anything within the Windows virtual machine...drop out of Coherence, everything works fine. Let us know if anyone has seen this...or if Parallels support can help us out. Thanks.