MicroC/OS II for ARM7TDMI Interruption problem

Hi,

I have one task that output hello world and delay itself for 5 ticks. After 5 ticks, the OS do the context switch. I verified this using the debugger and I see that PC now points to OS_Sched (+0xA8) (<— is this normal?) and the SP now points to task1’s stack, which is good. But after several instruction (2 or 3), the PC changed to 0x18! and task1 is never reached! I dont understand why this is happening. Do you have any idea?

Regards,

Fairuz