Application Hang after fired some events

Hi,

I'm created a VB.net smart device application and download into a touch panel with WinCE operating system.

At the beginning, I have tried to add component MSCOMM into VB.net to develop smart device application for Win CE, but it appears invisible...cannot be used. So, I download a communication library which call OpenNETCF.dll to develop my application.

I face one problem. The application i created and downlaod to Windows.CE is "Not responding" after few events (button clicks or the button enable and disable). The running application hang, all the button cannot be clicked. I must use Alt+ctrl+del to close my application.

FYI:

The Windows.CE is doing some serial communication with constant timer to polling data from other device.
The symptom happen when the data is polling and user click on certain buttons (like popup other windows and the "MsgBox" dialog.)

Can anyone give me some advice about this? Is there any other communication library I can use to develope my communication application?

Thanks for your helps.