Usb disk stopped working (FC3), partly solved

[Kristian André Gallis]

Hello!

I have been searching the web all evening but I have not been able to 
find any answer to my problem.

I have a usb disk, which after I used it for the first time stopped 
working when I wanted to remount it after unmounting and unplugging it.

I tried, but the response was

[root at localhost kristaga]# mount -t vfat /dev/sda1 /mnt/usb/
mount: special device /dev/sda1 does not exist

 From some messages here I saw the suggestion to run modprobe -r ehci-hcd

Then
[root at localhost kristaga]# /sbin/modprobe -r ehci-hcd
[root at localhost kristaga]# mount -t vfat /dev/sda1 /mnt/usb/
[root at localhost kristaga]#

It worked. But (seen from konqueror) now it is present in both
/mnt/usb/ and /media/usbdisk/ (the last is not working, of course, the 
same disk will probably not be mounted two different places).

My questions:

1. Why do I have to run modprobe -r ehci-hcd to be able to mount the usb 
disk?
2. Why does the disk suddenly appear two places?

Kristian André