>I get the following message "Library file p:\op\libs\opfw.vcx is invalid." I get that for 70% of my vcx's in the project. If I say ok, it continues and builds the exe. It also doesn't show any errors in the op.err file created after the project is built. I can open everything in the effected libraries. I can "Compile classlib *" and get no errors.

Make backup of your class libraries first. After that open each of them as a table in exclusive mode and PACK.