When I launch OmniGraffle (4.1.2) on my MacBook Core Duo 2Gb running 10.4.8, it basically locks up. If I wait for a few minutes, it might decide to show the startup windows, but if I interact with the user interface, its off into beachball land again. The app is unusable.

I'm not running anything else that would compete for resources, and the same version runs fine on my G4 iMac.
I've tried deleting the plist. Didn't help.

Can anyone suggest a fix?