Same issue again and again and put through troubleshooting of clearing cookies, caches, rebooting, etc... Was having this issue with Firefox and Internet Explorer.
Just had online chat and this is what I was told that On Demand programming is down for a min. of 2-3 days and at a maximum for up to a week while Comcast upgrades their systems "so that playback will be better. We are also making adjustments on our virtual drive so that we can make room for more programs."
She apologized if I hadn't been alerted to the maintenance/outage but when I asked if anyone had been alerted she said no, that the error code was the alert.