Usb device hdd with virtual cd rom

Hello,
i have an external disk drive iomega, wd, toshiba, all of them have a virtual cd rom partition.

when i attache it to the usb port, everything is ok, the partition of the cd, and the hdd are visible.
untill when when i remove, or saferemove the drive. when i attache it agane only the cd partition Will appear. untill i restart the pc.
that mean i can not use the same disk twice untill i restart .

thanks
oerating system: vista