Switch to the Xfinity Connect Lite version in Xfinity Preferences > General while using IE. Then open it in Firefox.

To me it is no longer a matter of a workaround to solve the problem. I have encountered this same problem from time-to-time. Eventually, I can get back to a stable system that works for awhile in the regular Xfinityconnect. Going to the Lite version means losing some functions. If Mozilla continues to have problems with Xfinity/Comcast, I think it is about time to turn up the heat on the Xfinity giant and threaten them with a law suit for illegal activities against the public. The volunteer programmers of Mozilla apparently have their hands full trying to keep up with all the changes thrown into the works.

I am sorry, but I want to know why this happens. I have my T-shirt that says Mozilla is the greatest. I contributed. Now let's work to get this damn thing to work so that it will be a totally resolved issue.

What is it going to take?

Question to the gurus. What part does turning add-ons on or off play in this equation/ I simply do not understand add-ons. I assume they add functionality but at what price? Where can i go to find what I have? Then which can I remove permanently and which should I keep no matter what?

Sorry, completely lost on this.

Any help appreciated.

Comcast Xfinity Connect worked fine for me on multiple different versions of Firefox for the first few months after Xfinity Connect was introduced in the spring of 2010. In June 2010 was when I started seeing a problem with not being able to get beyond the Inbox Preview screen in Connect until I clicked the View Entire Inbox button and watched the content reload, and had to repeat that a few times until the Inbox appeared. After a few weeks it just quit working at all, regardless of how often I tried to get into the Inbox.

Same damn thing regardless of which Firefox user Profile I was using - even a brand new Profile with no add-ons installed yet. IMO, Comcast screwed something up with Connect and Firefox when they fixed a different Bug. And it has nothing to do with the version of Firefox being used, I have seen the same problem with every version of Firefox from Firefox 3.0 up thru the latest 12.0a1 Nightly pre-release, development version of Firefox (12 different versions of Firefox, counting 3.5 and 3.6 which were major version releases).

We had a similar problem in the spring of 2008 when Comcast initially rolled out Zimbra for Comcast webmail (what they used immediately prior to the Xfinity Connect / Connect Lite interfaces), but that time they fixed it within 2 or 3 months, unlike now where they broke something that worked fine in the initial release.

See Comcast support and tell them that they need to fix Connect for Firefox users. Or just use IE when accessing your webmail at Comcast Xfinity if you can't use Connect Lite.