I had a Windows 8 virtual machine that I originally created in Parallels Desktop 8. Today, when I tried to reclaim disk space, it just spun for a while with no progress indication. I finally gave up, closed Parallels (not with Force-Quit, mind you, just normal Quit). When I came back, naturally, the hard drive was corrupted beyond repair. The parallels disk utility was unable to repair it as well (it just stuck at 0% forever). I'm pretty disappointed with Parallels 9. I just rolled back to 8. Luckily, I backed up this VM before upgrading to 9. I should note that I also had to deal with the Human Input Device problem so many others are dealing with.