When opening some dwg's in ADT 07 we get this fatal error:

FATAL ERROR: unhandled access violation reading 0x0030 exception at (then it lists a location...couple different ones)

Anyone know what causes this?
Others can open the dwgs just fine, and this doesn't happen on all the dwgs they open, just a couple.
I've looked for hotfixes, object enablers, reloading a profile, running a ccleaner for temp files and registry repair, defrag.

The next step is uninstall/reinstall of the entire program....really hoping to not have to do this.