Windows 7 has driver issues, it will try to install drivers for the cradle/drive and fail (you'll see under Device Manager, there's an exclamation against either a Disk Drive entry, or a USB Mass Storage Device).
If you un-install the driver for the affected entry, the device will be re-detected and suddenly magicly start working as you'd expect.
On other occasions, it can take over an hour (based on my 250GB test drive) for the DMS to be recognised - as I think the O/S does a complete scan of the disk for some reason.
By the way, the reason for this isn't a disc scan - the PhatNoise USB 2.0 cradles have an independent implementation of the USB Mass Storage Device function which reports a device class that Windows thinks it has a driver for. Unfortunately, there are bugs in the code that runs on the chip in the cradle which don't show up under XP or earlier. Since the PhatBox was de-supported long before Windows 7, neither PhatNoise nor Microsoft did any testing of that hardware on 7. There are some timing issues which can be exposed (causing the problems you see) with various combinations of disk drives in the DMS (taking different lengths of time to ACK commands), USB chipset in the PC, and PC speed. In my case, the Fujitsu 60GB drives used by PhatNoise (and other ones purchased elsewhere) work fine, but the Western Digital 250GB drive will always report an error installing drivers.
The solution to this is to use a USB-IDE bridge that doesn't require external code to work, and which is popular enough that Microsoft tests it for compatibility when they update their end of things. That's what the forthcoming PhatHack cradle replacement board uses.
