It's one of those moments that messes with your sanity. 

You need to run an stsadm command that is sufficiently complicated that you're tempted to copy and paste rather than to type just so that you can be sure not to fat finger it.   You paste the command into the command window, run it, and get the following "error":

Command line error.

Usage:

           stsadm.exe -o <operation> [<parameters>]

           stsadm.exe -help [<operation>]

Operations:

But you're certain that you've got the syntax right.  You have checked and double-checked and you know that you've got it right.  It shouldn't be erroring.  But it is. 

After trying it twenty times in different permutations, you start to wonder if it could have something to do with copying and pasting.  So you type it--and you type it exactly like it looks when you pasted it--and the command succeeds.   You proceed to wonder if you should rejoice that the mystery is solved or if you should curse yourself for not having become more suspicious of the copy and paste possibility earlier. 

This may not be all permutations of copy and paste of course.  It might be more apt to happen in multi-hop scenarios where I am copying from an the command window in an RDP console, pasting it to a particular chat window on my workstation, the customer I'm assisting then copies from the chat window on his or her side, and the customer then pasting it into a command prompt through yet another RDP session. 

Perhaps this combination creates some strange formatting problem.  The thing that drives me crazy is that its not something you can detect with the eye--at least I can't.  I've never debugged this kind of problem because I wrongly think that making a mental note to myself to never copy and paste an stsadm command again will somehow prevent me from doing it again.  (And a few months later I forget and have to re-learn this lesson.)