Real life e-mail conversation (if paraphrased):
J: Could you reset my password on System B?
IT: I've reset your password to X.
J: No, you've just reset my password on System A - I need System B reset.
IT: System B has been reset.
J: I still can't get on to System B - can you have another go?
IT: I've reset your password on System A.
J: No, I need you to reset my password on System B
IT: Your password has been reset.
J: I'm getting error Y.
IT: A minute ago you were querying System A, that is a System B error. I have reset your System B password.
J: Thanks, that works fine. But now I can't get onto System A - can you reset that password?
See, in all, she reset my System A password anything up to six times, and I can't guess which one of them she actually left it as.
I think my father would have been proud of the amount of swearing that took place a few minutes ago...
Oh, also, some systems require mixed case, others require numbers, others require that passwords are at least 8 characters long, others require that they are no more than 8 characters long, and all of them expire your password periodically and require you to set a new one, but all operate to slightly different periods.
Which means that right now I have about five work passwords to keep track of, perhaps six, in addition to my five or so home passwords.
It's not easy :o\