Corrupt stack problem in C/C++ program

I am running a C/C++ program in linux servers to serve videos. The program's(say named Plugin) core functionality is to convert videos and we fork a separate Plugin process for each video request. But I am having a weird problem for which sometimes server load average gets unexpectedly high. What I see from top command at this stage is that there are some processes which are running for long time and taking some huge CPU's.

When I debug this running program with gdb and backtrace stack,what I found is the corrupt stack: "Previous frame inner to this frame (corrupt stack?)". I have searched the net and found that this occurs if the program gets segmentation fault.

But what I know if the program gets segmentation fault, the program should crash and exit at that point. But surprisingly the program still running after segmentation fault.

What can be the causes of this? I know there must be some big problems in the program but I just can't understand from where to start fixing the problem...It would be great if any of you can show me some lights...

Thanks in advance