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: 
Gina, the real answer is in your comment above. You have to close down not just any Git bash window, but ALL git bash windows and then re-open one of them. At that point, `cd /f` will work. By the way, `cd F:` also works, as the bash terminal converts that to /f. I just confirmed this on Windows 7 64-bit.
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.