User developed DCOM service application crashes on windows 2003

Hi,
i have moved the DCOM service application from windows nt 4.0 to windows 2003. But when i stop the service, it provides me “could not start the service in a timely fashion and its state is showing as ‘stopping’. when the application in running state , after some time it stopped unexpectedly and record the event log as “Faulting application MobilTASAdmin.exe, version 1.0.0.1, faulting module ntdll.dll, version 5.2.3790.1830, fault address 0x00012009” and also showing memory could not read error.

My DCOM service application is built by importing some user developed dll and using multithreading concept.
Please provide me some information to solve the above issue as soon as possible.

Thanks.
sumoon