Matlab Crashes when interfacing with USB acquisition card

Hello,

I have written an application in which I receive signals from an acquisition card on the USB port. I use the card's driver which has a DLL with the functions for initializing, acquisition, setting parameters, etc. The thing is that when I run my application, Matlab crashes several times, it says "Segmentation Error" and gives me a list of all things that went wrong. Moreover, after many crashes and fiddling with the USB ports, the application DOES start eventually. To make matters worse, the crash does not occur on Windows XP, only on Vista and 7 32 bits; The card comes with its own application that works very well.

Can someone help me please?

Best regards, Jean