First thing to do is repair your disk permissions:
Run the Disk Utility application, selecting First Aid/Repair Disk
Permissions (OS 10.2.x) or the Repair Privileges utility (OS 10.1.5).
You can also take a look here:
http://www.entourage.mvps.org/errors.html#anchor-error_framework
concerning how to set ownership.
If those don't help, you may need to run Remove Office from the Value
Pack of your install disk, then reinstall Office and apply the 10.1.2
updater and any other updaters you need (I use the VBA Converter for
Excel X, for example, but most people won't need it).