Been having some weird problems with our webmail access to our mail server today. The MD of the company said it was giving him an error (which I eventually tracked down to the main page that comes up after you've logged in.) A couple of hours later, with no changes made, this page was coming up ok. When I then got home and tried to access the page with internet explorer (the best browser for Outlook Web Access) I get a http 500 error message, yet the pages are fine using Mozilla Firebird - ie6:0, Firebird:1 :-)
Will have to wait until tomorrow to see what the problem is as I'm not in the office!