Debug problem

Hi there,
i am using Visual Studio 2003 and Wismo Q2501B. I am running an application in debug mode through serial port and the debug process stucks in a little time after the start of debug. It is not a problem of the source code- wismo because i ve tried in another PC and it works fine. I am running these programs over MS Windows XP - Professional (SP2) in a P4@3GHz and 1 GB of RAM. Can somebody give me a tip of what is going wrong?
Thanks in advance
Kostas