I can see Parallels is doing their best to answer people's questions!! ;-(
Was this a Windows installation, or linux? I've had this exact same problem on my Ubuntu 12.04 installation. Basically, ever time there's a kernel update it screws up the Parallels installation, and it hangs. However, if I remember which kernel version I used, and choose that as the one I boot into, Parallels works just fine!
I sure wish Parallels would come up with an updater of some sort that checks for kernel updates, and then fixes the system when loading.
Hope that helped with your problem.
Robert