We're having a problem with the USB on the MCF52258. We're using it to transfer firmware from a PC to a device. The PC is the USB host and it runs Windows 7. The transfer works, but windows doesn't close the window till long after the transfer has completed. Looking at a USB trace, it looks like the problem is that the processor keeps sending NAKs after the transfer has completed which keeps the connection open. How do we keep this from happening?