Vista - Imation Flash Drive Reboot\Start-up Problems

I have a 4 gig Imation Swivel Thumb Drive that I am using with Ready Boost.
When I turn the PC on and insert the thumb drive it works great. If I
reboot or shut down and restart leaving the drive in when the PC restarts
the thumb drive no longer works. Removing then reinserting the thumb drive
gets it working again but I would just like to be able to leave it in the
port without having to continually remove then re-insert it.

When I checked Device Manager when the drive is working it shows up as a USB
Mass Storage device. When I reboot and it no longer see's the drive it
shows up as Unknown USB Device. The driver appears to be a Microsoft device
driver so should I be logging a bug and if so where can I do so? I don't
seem to have this problem when using a 2 gig Verbatim thumb drive so not
sure if this is an issue with the driver and\or with 4 gig vs. 2 gig drives
or Imation vs. Verbatim thumb drives.