NLS problem 7.13 -> 7.23

We have a suite of applications running on IDS 7.13 with tools ver 6. Non-NLS database on UnixWare 2.1.2 Yesterday we installed 7.23UC9 and tools 7.2 in a separate directtory - and to check everything was working brought the database on line and took it back off line again with 7.23 version of onmonitor. As we're not ready to deply on these versions yet, we reset 'INFORMIXDIR' back to our 7.13 directory. Now whenever we run our applications or any ver 6 tools (isql, etc) we receive 7203 and 7204 errors to do with NLS variable settings - DBNLS, LC_COLLATE, etc. We've changed absolutely nothing in Unix /etc/profile or the relevant onconfig file. Is it possible that bringing the database online with 7.23 has converted it to an NLS database. I can't export,drop and re-import because again, we get the same error messages when running dbimport. Any suggestions very welcome. Thanx