If you have a Windows computer, is your C: drive getting near full? On a smaller disk, you need at least 10% free disk space, and at least the size of your RAM reserved for the swap file.
Macs probably have a similar sort of functionality - if your system drive is getting full, your computer runs out of breathing space.
On a sidenote, I actually get the impression that the Club has better response time today, compared to recently. No more long waits for a posting to finish!
By the way, if posting is taking too long, I can stop the browser (IE 7) a few seconds after hitting the post button, and still the message pops up after I wait a little and do a refresh.