ERROR:
Access violation at address 230EF8CC in module 'QP5.dll'. Write of address 00000000.
WORKAROUND:
Try breaking up your large Procedure into smaller Procedures and see if that will prevent the error as it does not seem to happen on smaller Procedures, Packages, etc. (unable to get successful test on this though).
STATUS:
Waiting for fix in a future release of Toad for Oracle.