Sorry to dig up an old post. But this same problem happened to me recently.
It requires you go into firefox and delete the old certificates, then it starts working again.
tools -> options > advanced -> view certificates -> look for open-e.

While where on the topic of certificates I know alot of appliances use self signed certificates but the dss box seems to generate new ssl certificates all the damm time.
I really wish there was an option to disable the https admin and just use vanilla http.
Or if we can create a virutal interface on a management lan wouldn't be any security concerns.

The other security warning that drives me bonkers is when IE8 gets stuck.
"Do you want to view only the webpage content that was delivery securely"
http://members.ii.net/~avh/dss/dss_security_warning.png
Doesn't matter if you click yes or no the dialog box just keeps coming up.
The only way out is to open task manager and kill iexpore and start again!

And I think Open-E should implement the ability for users to be able to import there own SSL certificates.

lo/