Question: I use git bash under windowsXP system.I try to enter my USB Disk by entering "cd G:" in git bash,but it apears that "sh.exe : cd : g:: No such file or directory".

I can open my USB Disk under my system.

What's wrong with it ?How can i solve the problem?

Answer: 
If you don't want to close all bash windows, or that doesn't help, you can share the drive, and access the network share. Worked for me, usb stick at `//localhost/usb` works fine, closing bash didn't.
you can go down to the root of your computer by using the "cd .." command until you can go any further the copy the path from your flash drive and past it in the bash command. eg "cd D:\website" where D is the external flash drive.