Waiting for nonexistant latches

We're experiencing a rather frustrating problem on site here, We're running Informix OnLine 4.10, under Interactive 3.0.1 (Unix System V/386 Release 3.2) in a 486 box. Every so often (read ``once or twice a day'') our whole database system locks up, and an investigation of ``tbstat -us'' (users and latches) invariably shows one or another user waiting for a latch when no latches are displayed in the latches section of the tbstat output. The problem persists until a ``tbmode -z'' on the waiting pid clears it. here's the tbstat -us output Users address flags pid user tty wait tout locks nreads nwrites 804019b4 ------D 5899 informix ttypa 0 0 0 1704 35 80401a14 ------D 6594 informix ttypa 0 0 0 0 0 80401a74 ------F 5900 informix 0 0 0 0 0 80401b94 S-B-R-- 15458 tardis ttypa 804000dc 0 1 4029 0 80401c54 ------- 15764 emma ttyp1 0 0 2 272 90 80401cb4 ------- 16231 tardis ttyp7 0 0 1 779 0 80401d74 --B---- 15739 maxine ttyp6 0 0 2 326 85 80401dd4 ------- 16209 sysop ttyp2 0 0 1 21 0 80401ef4 ------- 15612 sysop ttypf 0 0 1 1471 0 80401f54 ------- 15609 sysop ttyp8 0 0 2 59 0 10 active, 56 total Latches with lock or user set name address lock wait user the `S' flag says `waiting for a latch' the wait column says tha latch being waited for is 804000dc, but there are no latches. a repeat of tbstat -us shows exactly the same situation, so it's not a transient problem. Additionally, the address of the latch being waited for is always the same. Anyone out there got any ideas? Cheers Bill Bill Hails <bill@clic.co.uk> Tel (UK) 01483 300 200 x415 Fax (UK) 01483 461 046