Solution or Workaround
Trying to reconnect to an SDE for Informix Database using a saved ArcView 3.x project may produce an error. As you try to open a project that includes such a connection, you may see a pop-up message stating "Database instance not connected".
If you look in the file SDEHOME/etc/sde.errlog on the SDE for Informix server, you will see a message similar to this one:
SDE_Database Error: -1
ODBC Error: IM002
Database Error: -11041
Error Message: [Informix][Odbc Informix Driver]Data source name not found and no default driver specified.
CAN'T OPEN INSTANCE: sde5152.
Spatial Engine Connection Failed (-158).
Cannot Get Access to Instance
The ArcView 3.1 and 3.2 project does not properly save the name of the database that contains the layer.
There is no current solution. This is a known limit.