I sometimes get this when the open client context allocation routines fail. Open client uses a localised message to tell you what's gone wrong.
Check your locales are set up correctly for the OS login your using. If the locale looks OK check it's in locales.dat. If it's not hack that file choosing one that's close to what you're using. The locales.dat has entries for a number of different platforms, ensure you're changing the correct platform.
I'm assuming the locales.dat can be found and you have setup $SYBASE and its associated variables ($SYBASE_ASE, $SYBASE_OCS etc...)