Hi Chris;
1) There are no PBD files used by the PB run-time system - they are all only DLL's,
2) SAP no longer distributes older PB releases. Especially versions that old.
3) PB 8 is long out of support and is not certified for recent MS-Windows releases
Can you tell us ...
a) Version & build of MS-Windows
b) DBMS version & build
c) DB Client used.
d) Recent changes to your application?
Regards ... Chris