The Activation key seems to be invalid!

Hi,

I have had a few problems with my Parallels Desktop, I have been using it since January no problem, untill a week or two ago, i decided to do an upgrade in which I found on this site. I installed this update and it corrupted the hard drive and would open. I uninstalled Parallels, and reinstalled it with my CD. I couldnt find my key code, I done a trial, but, I have found my old key code. But now its saying its invalid, what do I do?

Jon

 

Sorry, my OSX version is 10.5.2
Parallels Build number: 4128

 

any help at all?