I have two iCOM broadband radios that can be controlled by or exchange data with a Windows machine via a USB port. Each has its own individual Windows drivers for USB. One works with the Parallels VM and the other doesn't. Particulars: iMac, OS X 10.4.10 Parallels Desktop 3.0, build 4560 Windows XP Pro, SP2 The radio that fails is an iCOM IC-R1500 (which works fine on a non-VM setup). When I try to use the program, it puts up a message box saying "COM Port Error" and later a second one, "Communication failed. Cannot Access receiver". Otherwise it seems to run, but of course doesn't do anything useful. If anyone wants to look at the radio software - which includes the USB driver - it can be found here: http://www.icom.co.jp/world/support/index.htm This requires navigation to the software since the link always goes to the support root: Click Firmware Updates, agree to the license, click the Text "Communications Receiver", and finally click "IC-R1500 / IC-PCR1500 / IC-R2500 / IC-PCR2500" at the top of the right hand pane. This is a Zip file. If extracted, there is a subdirectory "Driver\WinVista". To install the Windows XP drivers run CP210xVCPInstaller.exe in that folder. There is no XP folder BTW, the driver does provide an uninstaller in Add/Remove programs If anyone has solved this, feel free to tell me how. I've looked around on both the iCOM and Parallels sites to no avail. There are some hints in the Parallels forums about USB to serial converters, but they don't seem to relate to what I have - unless that's what the radio has, hiding behind its USB port. That might be - the software, when it works, claims to be connecting to COMx, usually COM3. The other people talk about installing USB -> serial drivers in the host machine. If that's needed then I am probably out of luck, since there's nothing on the iCOM site, although the radio that works seems to talk about COM ports too... Oh yeah - I did try a Mac driver downloaded from SiLabs, the apparent provider of the Windows driver, but with no success.