50ms Timers instead of 100ms

Hi all I have attached a S7-200 program which is puzzeling me. When it runs on the PLC the two timers T41 and T50 behave as if they were 50ms timers and not 100ms timers. If someone could have a look and see if there is anything in the code that could cause the timers to do this I would be greatfull. The timers are located inside the Dump Control block and are symbolic named DUMP_TIMER and START_DUMPING_TIMER

Thanks in advance all

Jonny