This annoying behavior, also present in Outlook 2007 and other Office programs, mostly occurs when the clipboard has HTML formatted content (like when you copy content from a website to the clipboard).
Would anyone know how to get rid of this permanent? Which server is Office 2007 trying to connect when you working in a local environment outside any network.
One of the possible solutions is to do a "Paste Special" (click the down pointing arrow near the Paste Icon) and select "Unformatted Text" instead of the default "HTML format". Or you could have the Scrubber running in the tray that auto converts clipboard text in plain format.
Favorite Microsoft Office Command - Format Painter