Heave network programming stuff

I have written a program that makes it possible to use the comport of the server to control a micro-controller interface.

This works fine when I run it the first time and connect to the server. One command runs very well, but when I send the next command the server receives the message, but doesn't send it to the comport. The client/server part is in C# and the comport wrapper in VB.NET. Does this make any difference for my program ?

When I wait about 30-40 minutes the program works again for one time :S (I keep the server and the client connected and the comport opened). Is this some buffer or object that isn't correctly handled ?

If you need some code, please reply. I won't post it if not asked, since it's too big to post without a reason

try checking the status of Opening/closing the ports. open/close several times. does your comport support speedy operations , I mean how much is the baudrate etc.

another stuff I would like to know is ,
are you using COM dlls inside, which type of server you have developed.

Paresh

My comport settings are:

Baudrate: 9600
Parity: none
Stopbits: 1
Databits: 8
Flow-control: Xon-Xoff / Hardware

So, this is kinda slow.
I use windows API calls for the comport wrapper. Maybe that might be the problem :) some buffer or setting not properly used ?