For some reason the Firefox developers seem to have taken protecting end users to a rather inane level, as the errors displayed for self signed certificates are extremely confusing.
See below for an example:
Of course if the site you are connecting to is a public ecommerce site then maybe you should consider your options very carefully, but when it’s something like a hosting control panel for Virtuozzo you need to be able to access it.
If you look at the bottom of the screen you’ll see a little link: “Or you can add an exception”
If you click on that and then follow the steps you will be able to access the site / control panel without any issues.
With older versions of Firefox this wasn’t as much of an issue, as the warning message was a nice big popup.
The new version of Firefox handles this situation very badly.