Thanks for the tip, bellvuebob. I didn't do anything to my browser and tried the recording button again today and it works like it did before. Now I don't know if some random change to my browser or a fix by comcast corrected the problem, but whichever, I'm glad that that part is back to the way it used to be.
Now if they could only fix the time-jumping problem. And while they're at it, I wish that either on the DVR itself or on the website they would give us a way to jump into the future to set a recording. I hate it when I see that such and such a show (which I would really like to see) will be aired on Thursday and I can't jump my guide into the future to set the recordling. Sure, I could go forward 3 or 4 hours at a time to get there, but what a pain.