Ok, now my third experience:

- Unplugged and let it completely cool down for about 4 hours.
- Running GS for under 10 minutes. Being very careful to press a button only once every 2 seconds.
- Becomes a "Slow Remote" at around the "SetTopBox Brand" screen (a long list of brands).
- Again, CPU quite hot but PSU heatsink even hotter. Maybe not as hot as last time, but my finger is pretty subjective.
- I rebooted (into GS mode). Became "Slow Remote" immediately.
- I tried uninstalling the TurboWeb card and turning off TivoWebPlus as soon as terminal became available, but still became "Slow Remote" immediately.

Three things I conclude from this:
1) Time seems to be less of a factor than I thought. Maybe because a component can just as easily overheat in 10 min as 2 hours. Or maybe because it is actually a software problem after all. But then why would it begin to "slow" immediately.
2) It always seems to happen when a long list is displayed. Maybe because that loads the CPU more...
It must be a hardware-software interaction. Maybe higher CPU load overheats a component faster. And maybe with an unstable overheated component, another bit of software is more likely to "slow". But that is a whole lot of maybe's.
3) Maybe I don't have the same problem the rest of you have - maybe I have a more seriously faulty peice of hardware.
I mean, I should be able to make it through more than 10 minutes!
Then again, maybe it is the same problem, just amplified, which makes it easier for me to replicate and experiment with.

So any ideas anyone has would be great. I am willing to be a lab rat, but bear in mind I have no broadband at home, and I am currently having trouble telnetting in (I can only connect as tivo boots, and then connection is lost in under a minute!). Terminal works fine.

If a fellow Cantabrian would be interested in a meetup, then maybe we could try swapping out components (like the PSU) and hopefully identify the offending peice.