4GL HANGING PROBLEMS

Situation: I am using a cursor declared WITH HOLD to step through a series of records. I have two other cursors, an update cursor to lock the row and a normal cursor tpo refresh t he screen details, which are used as I step through the rows. All three cursors are prepared at the start of the function. During operation the user can perform a series of transactions relating to the screen record which requires the record to be locked first of all, and then the transactions are committed or rolled back at the end. Problem: This works ok for a random number of times until suddenly when rolling back the system will hang. You do not get any problems when committing work. I am using Informix 4GL 4.10 on SE. Using the output from tbstat it does not seem to be a locking problem. Any ideas anyone????? as this is really starting to be a bit of a pain.