Yes. Well, I clicked on the spot where the free registration box would appear (because it hadn't fully loaded the images yet). I registered Avast on my laptop over wireless so I knew where the command boxes would appear.
On my desktop, (1) I clicked register from the interface, (2) the registration popup box partially loaded and I clicked on free register, (3) it disappeared as if it accepted my choice, (4) I observed network activity on the task manager for an extended period of time, and (5) it simply went back to the interface and network activity dropped to zero as if nothing was accomplished. I then re-clicked on the register button from the interface and went through the same process a couple of times. No luck.
By the way, I did this same process a few weeks ago, gave up, and installed Panda. My original Avast was painfully downloaded over dialup and had been on my PC for a year. On the same computer, I had no problem registering from within the interface a year ago, but it wouldn't let me re-register. But I didn't like Panda much, so I downloaded another Avast setup file to try again. I had the same registration problem this time and had to register offline, which was successful.
I have a third computer that I could try it again on if there is something else to try.