There was a change in the ROWID format between Oracle 7 and Oracle 8.

I have seen certain apps that do updates by using the ROWID (update table BLAH set .... where rowid = #####)
fail with this error because they are expecting the old rowid format and suddely the database has a new format for rowid.
Borland's 16 bit BDE (Borland Database Engine) will do the same thing, and the only way around it is to use the 32 bit BDE.

I don't know anything about VB, but you might be able to fix yor problem by recompiling your application with a newer version of it. Or, if your app is using ODBC, maybe you need a newer version of ODBC.

-John