So there's a problem with the path - maybe something the command line is parsing differently from how it appears in the GUI. I don't have a Windows machine I can look this up on, so you'll have to work it out. Try just typing the command "dir". Do you see anything that looks like the documents and settings (but may not be "Documents and Settings")? If so, cd to that (cd directoryname), then try cd shaheem\desktop. Then use the fastboot command with no path.
I suspect it's the first part of the path that's causing you problems, but as I say I don't use Windows so don't know why (does the DOS command line use upper case, not like gaps in files names, or..? Just not sure because it's so long since I used this).
It might be that those quotes are needed to work around just this type of problem (the command line sees the real directory names, which are not what the GUI shows). If so another answer will be that you use the quotes, but you got have something inside them wrong. Compare exactly with what you see in Windows Explorer - case sensitivity may matter, beware of double spaces, but you have mistyped something.
It's not that the command doesn't work, but some part of the path or name is wrong.