I have similar issues with some of my sites using IB5.6 and IB6.0.2.0,
I cannot replicate this in my test rig, and I have checked my commiting
code numerous times to make sure I am always calling either a .commit or
a .rollback , but I get I huge gaps in transaction statistics, I cannot
do a sweep as the gap is not between the OIT and OAT (see example) so my
only option is a backup and restore. I have tried IB_AFFINITY to set it
to one processor in the dual processor machine, I have also had the IT
team turn off hyperthreading in the bios, all to no avail.

OT 566738
OAT 566739
NT 940551
OS 564916

After checking this weekend the OT,OAT and OS have not moved from above,
but the NT is now more than a gap of 1 million to these other stats..

Mart