security problems

Hi Deepika, this is really a big topic to discuss without any prior knowledge of basic programming problems,

At very lowest level i can only say problems that can occur includes deadlocks, resource allocation, management of logical and physical clocks, event management, concurrency in results, error prone outputs, process files and event locks, scheduling, handling of process pool, transfer in process state information etc.

Though they appear as regular OS problems they are actually reason of bigger security problems.

In wide scope there are many that are usually included in memory management, process management, resource management for knowing more i recommend you read following books

Operating System Concepts and Principle by Greg Gagne, P.B Galvin and Abraham Siberchatz
and
Distributed OS by Sinha or Andrew Tanenbaum

Happy Computing.

thanks....... n ya,,,,i just got the book by GALVIN