Outlook 2007.
OS Vista Business

I don't think the problem is caused by a virus because I've run several
different antivirus programs and came up empty-handed. Here's the scenario:
Yesterday an e-mail appeared that was clearly a sales pitch (I no longer
recall the product). Most of the junk I get is effectively shunted off to
the junk pile, but not this one. When I clicked to erase it, it transformed
into a blank, except for a box that invited me to click in it so it would
not appear again. I innocently clicked and presto--all my Inbox e-mails
disappeared. I think, but I'm not sure, whether the offending e-mail
disappeared, too. Fortunately I back up my e-mail regularly , so I was not
terribly distressed. The next day, I discovered the image shown below as the
first item in my Inbox; I don't know whether it was there after my emails
vanished the day before, because I was sort of preoccupied. Since I had
backed up again, I risked trying to erase it again, and of course all my
emails disappeared again except for that one blank email. I poked at it, and
lo and behold, all the "lost" emails reappeared. I somehow think it's an
Outlook bug but I can't confirm that.

Thanks, Will