Windows Live shows Working Offline when I never asked it to!

For the past 24 hours, my Windows Live email has continually shown a "Working offline" and large red X in the lower right corner of my screen.  If I click the "go online" tab on top of the screen, I get a message telling me I'm currently working offline, and asking if I'd like to work online.  I click "yes," and it shows I'm online until I attempt to do something, like send or receive emails, at which point it immediately says I'm working offline again.  I've gone through this routine dozens of times.  I've rebooted the modem, and even tried reinstalling Live, but nothing changes.  The emails are coming into my Virgin account, but not being transferred to Live Mail.  I've never had this problem before, and it's probably down to something I've accidentally ticked, but I'm at a loss...  HELP??  Thanks!