If you press enter just after pasting a link in the editor pane, anything you write underneath will be part of the hyperlink, even if it is styled normally.
How to reproduce:
Go to your browser, select the url in the address bar and copy it.
Go to MyInfo (tested with fresh install in a clean windows XP SP3 machine) and paste it in the editor pane. Press enter and write anything below the pasted url. Everything below the link (even multiple lines) will also link to the url.
If instead of enter you press space or tab you don't experience the same problem.