What was the time between your Private Message "tries"? If you do not wait for at least 5 minutes, the Forum software perceives it as spamming.
Have you logged out of the Forum, closed all browser Windows, then open browser, log into the Forum, then try to send a Private Message?
Have you cleared all of the browser cache?
#IWork4Dell Find your Service Tag If still under warranty, click the "Get help now" icon on the right to start a live chat session. To send us a private message, click our DELL-Cares username. Our Forum profile page will then appear. On the right, click "Send this user a private message".