The Casper Admin preference plist is likely corrupt and is scaling the window in a weird way. Just locate the com.jamfsoftware.admin.plist in your own Library folder, and either delete it and relaunch Casper Admin.app, or, if you'd rather not lose other settings for the application, you can manually edit the window width and height settings
defaults write ~/Library/Preferences/com.jamfsoftware.admin.plist windowHeight -int <somevalue>
defaults write ~/Library/Preferences/com.jamfsoftware.admin.plist windowWidth -int <somevalue>
Change the <somevalue>'s above to a window pixel height and width that makes sense for your Mac. For example, you could set it to something like 800 x 600 initially and then drag the window back to whatever size you want later.
Great thanks this has resolved the issue.