Trouble Implementing External Procedure on Oracle 8.1.6

I am a Oracle novice with a little bit of knowldge, which probably makes me  very dangerous or perhaps even useless, however, if you can manage to overlook my lack of experience to answer a quick question, I'd be very greatful.

I have created a stored external procedure which works absolutely as it should in Oracle version 8.1.5, but when I took the very same files I used to create the library and procedures to version 8.1.6 [the only changes being in the location of the DLL used for the library], I get an access violation on extproc.exe and the following four errors:

ERROR at line 1:

ORA-28576: lost RPC Connection to external procedure agent
ORA-06512: at "SSA.LOU_SSA_N3SGUS", line 0
ORA-06512: at "SSA.LOU_SSA_GETKEYSTACK", line 43
ORA-06512: at line 1

The first error seem to point at my dll, the next three at my PLSQL code, but I don't buy this because, as I've already stated: it all works fine on 8.1.5, so I'm figuring it's really a problem doing with a difference between how 8.1.5 handled external procedures and how 8.1.6 now handles them.

Has anyone experienced a similar situation and has found a resolution they could share with me? I've checked technet and came up dry and on metalink I  saw a couple of similar problems posted, but never the solutions.

Thanks for your help,

Lou da Silva

PS
PLATFORM INFORMATION:
Oracle 8.1.6 Enterprise Server, release 3, Windows NT4, Service Pack 6 Received on Thu Mar 01 2001 - 16:14:11 CST