When visiting sites over HTTPS that use a self-signed or expired certificate Firefox will stop dead in it’s tracks with a “This Connection is Untrusted” message. Annoying but necessary given the web-savviness of the majority of net denizens nowadays.
On occasion when clicking “Add Exception…” the option to “permanently store this exception” will be greyed out. Very annoying. Especially when it’s my test server and I created the self-signed cert and I KNOW it’s not valid.
The only reliable solution I’ve found is to delete (part of?) Firefox’s certificate database. The file (on Windows 7/Vista) is:
Note, you will have to quit FF first. Annoying.
Note to self: try and find a HTTPFox clone for Chrome so I can finally free myself from this awful browser.