This is a forum for CrossOver Mac and CrossOver Linux, not a Vista support forum.
That disclaimer being said, I had to copy the WPO12 directory from my WP disk to my hard drive, then right click on setup.exe and in the compatibility tab change to Windows 2000 then check run as administrator, then run setup.exe to install. Installing in this manner allowed WordPerfect to run and save files. The current WP install would have to be uninstalled first and if UAC is turned on you will have to click allow each time WP is started.
Before all of this effort, you might try unchecking "Use enhanced file dialogs" found in tools/files/document which solves a save document problem in CrossOver.