Windows 7: Removable devices USB port drive letter issue

I have two monitors that have ports for USB and memory card built into the side of them. When the monitor is plugged into the CPU they are assigned drive letters and become available for use. The problem I'm having is that they are sometimes interfering with my network assigned drive letters whereas they take the letter(s), J,K for instance even though it is reserved for a mapped network drive. Question: Is there any way to permanently assign drive letters to the removable devices (ports) so there is no chance that they will take my mapped drive letters?

Thanks for your help.

I've had this issue before. The only way I found to rectify this was by changing the drive letters to way down the alphabet. My USB device wanted "G:" for some reason which was a mapped network drive. I fixed this by re-assigning the mapped drive to "Z:" but I did sort out another PC by re-assigning the USB drive letter to "Z:" and left the mapped drive as is. Hope this makes sense as even I'm cafuzzled now