INFORMIXSERVER / DBSERVERNAME limitations?

Hi all. I had an interesting problem Saturday night (aren't all problems more interesting on a Saturday night?). I am running IDS 9.20.UC3 on AIX 4.3.3. The instance hung in a checkpoint (CKPT REQ). I have seen this before and support claims it is an existing error in our version. I can live with that. However, after bouncing the server (and, obviously, the instance) no client processes could connect. Neither our software nor our web site could connect to the instance. All onstat commands I ran showed the instance up and running. However, dbaccess would hang on the 'select database' screen just showing 'Running ...' and onmonitor would clear the screen and hang, not showing even the initial menu. After bouncing the instance and the server a couple of more times, I grasped at a straw and changed the INFORMIXSERVER and DBSERVERNAME from 'online_resusa' to 'onres'. Brought the instance up and all was well. Dbaccess and onmonitor all behaved as one would expect. Once the ODBC configurations were changed all client processes could connect again. Before taking this step, we had rebooted the DNS servers and anything else we could think of that was between the client systems and the server, to no avail. The original INFORMIXSERVER, online_resusa, was not a new thing. This system has been up and running for well over a year with that value. I cannot find anything in the documentation that indicates that my INFORMIXSERVER value was invalid in any respect. Informix support is "researching" the issue. Any thoughts? Also, when did IBM change Informix support to by 7 to 7 central time, Mon-Fri? Not much help on a Saturday night to discover that, as a 24 by 7 shop, I am covered by support less than 50% of the time. Thanks, Dan