I've just installed V5, after reading the warnings about the BSOD with multi-cpus I changed cpus to 1 before the upgrade. The upgrade went very smoothly (I was pleasantly surprised.) One of the reasons for upgrading was to try the new maclook and Crystal features. I have two VMs, one XP SP3 and one Windows 7. I had tried maclook in win7 and crystal without much issue. When I went to turn this on for my XP VM, on the mac side prl_vm_app rocketed up to 110% cpu usage from around 15-20%. Inside the XP VM, things were almost non-responsive. Launching proxexp (process manager replacement) showed that the shell explorer.exe was running about 65-75% of cpu constantly. Turning off maclook returned everything to normal. I tried starting the VM and re-enabling maclook as well as rebooting with maclook enabled. It appears there is some strange interaction between the maclook theme and XP. Note, I didn't have to run crystal for this to happen, simply use the maclook in "Window" mode. I didn't see anyone reporting this issue so I thought I would tee it up. Note, the Win 7 VM running in window mode (View->Window) with maclook enabled was fine. I turned this off as well to see if it had any effect on the other VM and it didn't seem to. Lastly, does anyone know of an XP hack to make double clicking the title bar lower the window like OS X does? I was hoping that maclook was going to support that feature which appears to be one of the last UI related things to make the integration complete. Thanks -Fred