When I log into outlook.com, I get the normal Microsoft 'outlook.com address', but as soon as I start viewing my inbox emails, or try to delete 'sent' items, or open a new folder - the address changes automatically to https//dub.125.mail.live.com

My question is - what is this dub.125?  Is it a virus in my email account?  Is it a phish?  After a little while, the mouse also then stops opening items to view.  Does anyone have any suggestions?