Well without a make/model number not much advice can be given.
I would start by going to the manufactures website and seeing if you can download a firmware update; this could reset the device so its not trying to connect to the web, where you go from there depends on what you want to do.
It might be worth baring in mind that these devices are not supposed to be used at home i.e. there designed to be used with specialist warehouse software or specialist applications - you might find it hard to just plug it into your computer and expect it to appear magically.
I'm guessing the software is on the computer, not the device itself? If that's the case, the best course of action would be to intercept the data before it reaches the software. Considering that a Serial Port is Analogue and not Digital, that shouldn't be too hard.
Always keep the problem as well as the solution guys. Other people will undoubtably have the same problem!