arduino communicating with matlab problem

i wanted to communicate between arduino and matlab and i have written all the codes and it is running successfully but the problem arises after 4-5 min. of serial communication between them that matlab is not able write data to arduino, it is showing error:

    ??? Error using ==> serial.fprintf at 144

    An error occurred during writing.

    Error in ==> sectioning_with_arduino at 87 

    fprintf(s,'%s\n','2');

what is the problem i am not able to understand?...is buffer on the port gets full and matlab is not able to write data on it again?.... please help

thank you