I'm testing out Informix using the developers edition 11.50 on Windows XP, since a customer uses Informix for their database. I have been able to connect to the database and make changes with the default informix user so I know my connection string is good. But when I use a different user I get the -387 error "No connect permission."
1/2 through writing this I switched to IE and lesson learned, don't use FireFox with OpenAdmin. It caches things weird and causes headaches.