VMs on external hard drive with two macs

Greetings All,

I have VMs for Windows XP, Windows Vista and Windows 7 on an external hard drive. I have Parallels 7 installed on my mac-mini and my macbook pro. I set up the VMs on the Mac-Mini, and when I try to mount them on the laptop, I get an error message saying that the VMs are corrupted. I can run them just fine on the Mac-Mini, but they won't open on the macbook pro.

Can anyone help?

Thanks in advance,
John Miller