I'm using Tiger to connect to a web-based exchange e-mail server. It all worked fine until a couple of days ago, I now get the message

local security cannot be contacted

and I can no longer read my mail. If I use firefox it works just fine, if I switch local users and connect with safari it works fine. Rebooting does nothing, I've cleared cookies and passwords to no effect. No other mac users has this problem. Any suggestions??