Error "Unable to Load the Parallels Driver" After Updating Host from Leopard to SL

I currently have a host that is running Parallels 4.0.3540 with a Windows XP guest. I just upgraded the host from Leopard to Snow Leopard, and now when trying to start my VM, I receive the error message:

"Unable to Load the Parallels Driver"
Please restart your Mac and try again.

After restarting, unfortunately, nothing has changed.

 

If reinstalling PDM4 doesn't work it's probably because PDM4 doesn't support SL, I don't remember exactly which version supports which OS X version, but it's likely the case, I'm almost sure SL is only supported in PD5 and above.

 

Thank you so much for your post. I used the "Previous versions download links" in your signature, and installed 4.0.3848. After installing, I was prompted that the Virtual Machine had become corrupted and could be repaired from a valid backup. A few seconds later, everything seemed complete and the machine booted up perfectly. All seems to be working now.