Rthread resume function on target hangs the phone(P990)

Hi I am facing a strange situation

when i create a gui application and create a simple thread which start from one of the menu (Capability None)its working fine RThreads resume works fine both on target and emulator when in the same application in the thread function if I call huge codes which creates some more thereads(Capabilty None )
The Rthread resume function on target hangs the phone(P990) but on Emulator everything works fine

Can any body suiggest what could be the reason for this strange behaviour.