another person was having the same problem with windows 7, maybe his solution will work for you: this is from his post I personally don't have the cutter or windows 7, just trying to help you. :Here is the whole thread for links
if you are experiencing the dreaded uscutter under unknown device in device manager have no fear. This is all assuming that you have already tried the normal steps and installed the FTDI driver of course. First download this driver HERE and extract to a folder in a spot you will be able to find later. Then go to control panel, devices and printers and choose to add new printer. Add local and use the existing port usb0001. When it is looking for the driver choose have disk and navigate to the directory you saved. It will tell you that this driver is not digitally signed but this is ok.
Now launch SB and create a square. Click cutter and then setup. Choose your cutter model and under ports choose usb0001. OK out of that and then choose cut and cut tile. This has worked on both Windows 7 64 bit business as well as Windows 7 32 bit ultimate and I was able to duplicate no problem.
Simple solution? Yes! Does it work? It did for me!
keywords: windows seven com port usb device not found driver 64bit mh-721 mh721
footnote: This is my experience with my particular situation, yours could be different. I am providing this to help others in case they have the same issue. "Human Knowledge Belongs To The World!" - Milo Hoffman - Antitrust -