after certain amount of execution...Status Code: -200088

Hi,

I am using USB6009 two DAQs with visual studio 2010 (c++), operating system window 8.1

Previously, I have performed same kind of task without mutilple functions. Now I have increased no. of while loops and functions in the code. I am using digital lines port0/line0:7 for both Daq.

In the code, certain amount of time (Ex. 3 to 4 times) code executes properly. Then it throws error

DAQmx Error: Task specified is invalid or does not exist.

Status Code: -200088

For every new complication, behavior is same.

I suspect that, due to no. of while and functions are increased it is killing the tasks. One of task is getting stop and other is not. Can anybody suggest me solution for this. Please its urgent for me. My requirement is program should execute continue as it was working before. 

Thanks in advance.