Windows cannot change the password

I came through a very strange problem with my Vista running desktops. I also have a HP laptop with Vista Home Premium and i dont have any problem changing its password but when i try the same on my another two desktop the same Vista Home Edition, it gives me an error message saying:

"Windows cannot change password"

Any idea what could be the reason? Is there any thing blocked from the registry? Please help. Many Thanks.

Hello kUnDaNlAaL, i had exactly the same problem with my brand new laptop couple of months ago but i fortunately managed to fix it my own. Here is what i did.

I went to user accounts, created a new administrator account with complete rights. Logged off and logged in to the new Admin account and tried changing passwords for any user accounts. It worked like charm. Try this out, it is the easiest way.