Problem creating temp table

This one had several of us puzzled all day (still has, in fact). Any of you folks got an explanation? Environment, 4.11 tools, 4.12 On-Line, HP-UX 9.04. A program has run at about monthly intervals for a couple of years or so with a statement CREATE TEMP TABLE x (...etc....) followed by INSERT INTO x SELECT ... etc..... Last night it broke. My colleague who normally runs it is on holiday so it was being run by someone else. It threw error -270, cannot position in a temp. file, C-ISAM error 101, file not open. This seems to have been on the CREATE. After trying all sorts of things such as su to the regular user ID, checking the value of DBTEMP, making sure there was plenty of room we arrived at the following: Even in a cut-down test program the code broke when fully compiled. In isql and p-code 4GL both statemnts run perfectly. The environment makes no difference. The test program was then recompiled with the temp name "x" replaced by something else. It ran. It was then recompiled again with "x" reinstated as the temp name. IT STILL RAN! Exit several Informix programmers gibbering quietly... Any ideas, anybody? Ian