Running Toad 11.5 on Window 7 with Real PDF Printer set as default printer will cause the following error Toad:
Access violation at address 00403BD7 in module 'Toad.exe'. Read of address 00000000.
WORKAROUND: In Windows 7, go to Control Panel | All Control Panel Items | Devices and Printers and change the defautl printer from Real PDF Printer to something else.
STATUS: Waiting for fix in a future release of Toad for Oracle