If it's a hard drive, it could really be either drive.

Considering the array of problems, you might want to get a UPS in case power fluctuations are at the root. More info here:

http://www.weaknees.com/protect.php

I ordered a UPS to test that out. Our power can be a bit wonky sometimes. I'd never thought about that before, but our home desktop sometimes resets itself while we're at work too, so that could be the problem.

If it continues happening, how do we determine what hard drive is at fault? We had problems with pixelation and random resets before we got the expander (got the expander for the Olympics, so sometime in August). The No-signal issue is new, though. Only been happening in the last week or two. And today after a hard reset, the tivo got stuck after booting up and getting through the tivo video. The red Now playing screen came up, but no menus were on screen. Hard reset again fixed it.

You'd have to test both drives in a PC to determine which drive is bad.

Or, you can pull the Expander (and lose all content on it) and see if the problem goes away. If it does, it's the Expander.

I plugged the Tivo up to the UPS and it seems to be working pretty well. No more no-signal messages since we got the UPS. We did have one day when the Tivo froze, with a purple-ish screen, though. Any idea what that might be?

Not really, but one problem, if it's isolated, really shouldn't be cause for alarm.

We're still seeing problems with the TiVo. So far we've encountered four different scenarios of Tivo not working correctly.

1) Turn on the TV to find a frozen screen with green and purple/pink colors, hard reset needed.

2) Turn on the TV and as soon as Tivo is interacted with (hit any button) Tivo restarts itself, works fine after.

3) TiVo resets itself during playback, works fine after even during same show playback.

4) Turn on TV, see 'No Signal', even though all cords appear to be in place, hard reset needed.

I've run kickstart 57, 58 and 52. I've tried to run kickstart 54 but it freezes after I select run SMART tests.

We were experiencing problem #2 before we added the DVD expander, but the other 3 are relatively new problems (in the last month, though we've had the TiVo since the beginning of the year).

We got the DVD expander in August for the Olympics.

Any suggestions?

This really does sound like a hard drive problem.

I'd guess it's the A drive (internal) since #2 existed before the external was attached, but it could even be both.

I'd recommend removing the external, which will force deletion of most shows. Then, if you still have problems, you should try an internal replacement from here:

http://www.weaknees.com/s325.php

You should get one large internal, and not use the external, because a replacement internal will not automatically see the external.