I started Parallels on my iMac and there was a new update, which (as I thought I have the time) decided to download and install.
Well it took ages to download the disk image and when it finally did get downloaded, I am guessing it did not mount correctly as first Parallels froze and then the whole Mac.
Generally when an application fails to behave properly on a Mac, you can shut it down even force it to quit, but everything else continues to work. Today with Parallels that wasn’t what happened.
With the whole Mac not working, I gave it five minutes and then holding down the power button forced the iMac to shut down.
I restarted the Mac and everything seemed to be okay.
I mounted the Parallels disk image and ran the upgrade installer, which worked fine, and then updated my virtual XP machine which also went fine.
Not sure what went wrong, but XP on Parallels is now working fine.