USB Drive Letter Conflicts

Flash drives were not showing up(O bytes used 0 bytes total) after showing error message from using a write-protected flash drive. They show up if I change drive letter to something else. I deleted infcache1.ini,deleted and uninstalled flash drives and even used USBOblivion to delete traces of registry files, but E:still wants to be used(drive letter conflicts) Are the Usb inf files files corrupt or something. Does it have anything to do with autorun.inf or anything like usbstor.inf. How Do I fix the files and do i need to reinstall chipset drivers. I've been dealing with this for over a month now.

The Flash drives show up like this:Have only two usb ports.Plug in one drive, then another next to it, they both show up E: and then F:. Then I unplug both add a third it shows up. Unplug that one and add the first flash drive and it doesn't show up. Restarting computer makes it show up again. Help!

 

What operating system is this? XP, Vista, 7, 8?

 

WIndows XP

They have been removed correctly

I managed to mess 2 of 3 computers with the same flash drive(write-protected). They have plenty of USB hubs. The one I'm using has only two usb ports and it not an important computer as I'm using it as a test computer to fix the problem before trying it on the other computers.
I have one of those usb hubs. I haven't tried it though. Maybe I should just to see how the drives show up