A very slow Internet connection would also do that, as you would likely reach a timeout before getting the chance to download the small bit of data needed to access chat. I had this problem when I was using an old mobile modem, some years back, on two versions of the RealChat software. There may be a way to get past the timeout variable, if it is your 'net. I'm sure Firefox has just that option, on its hidden about:config page. I got it working, somehow; all I needed to do was download the data once, for it to be stored into the cache, and hopefully stay there for as long as needed.