Hello,
Most probably the user is trying to open Parallels with a link broken, or he/she has moved the folder of the virtual machine (which contains the hard drive) and Parallels Desktop now can't find it.
Please, try the following:
create new machine and mount .hdd file (which is machine's hard drive) to it from the "old" virtual machine:
- run Parallels Desktop (Finder -> Applicatons -> Parallels. Press and hold Apple button immediately after double-clicking on Parallels Desktop's icon).
- See the PD menu at the top of the screen -> File -> Press "New" button and follow the Wizard.
In the first window, please, select Custom installation type.
- When asked to choose between Create a new hard disk image or Use an existing hard disk image, please choose Use an existing hard disk image.
- When asked to select a hard disk image file specify a path to it (by default it is - User -> Documents -> Parallels -> Windows XP (or Windows Vista) -> If the machine is XP, than a disk should be called like winxp.hdd, if Vista - then winvista.hdd).
- If there is no .hdd there, try to search for it in Finder's Spotlight.
- Clear "Start Windows installation" checkbox before clicking on "Finish".
- Start the machine