Ext. HD being blocked by macbook running Parallels

Hello! I'm running Parallels to use WinXP on my macbook and for some reason cannot view my external hd in winxp. I connected the hd to a windows machine, and it was detected just fine. I changed the settings in the USB Controller in Parallels to "autoconnect on". When I start up WinXP, it then detects it, however it says another process is blocking the device.

Does anyone have any ideas?

Moderator, this should probably be moved to the Bootcamp and Parallels forum. It might get a readership there that knows the answer!

Thanks! I'll take your suggestion