bootcamp usb drive problem (P3.0 build 4560)

I have a USB drive that is formatted as MS-DOS (FAT32) for transferring large files from mac to pc, etc.

I have Parallels 3.0 (build 4560 - same with previous versions) using Bootcamp mode.

Parallels won't start the virtual machine if my USB drive is connected.

Since bootcamp will only run from the internal drive of my MacBookPro, as per the restrictions of being able to install windows on bootcamp in the first place, I cannot see any logic as to why the presence of an external USB drive with a DOS partition on it should prevent Parallels from starting the virtual machine in Bootcamp mode.

This is really annoying because the USB drive must be physically disconnected before Parallels will start the VM.

Please fix.

Mac OS X 10.4.10, 1.5GB RAM, 1.83GHz core duo
Win XP SP2 in Bootcamp partition, installed with bootcamp installer.
Parallels 3.0 (build 4560)
USB hard drive with 2 partitions: Mac HFS+ and DOS FAT32.

Regards,
Matt