worm wrote:So, anyone got any clever ideas?
Not clever - just reasoned.
Go back to using the network - if you aren't sure what you have and haven't changed - reimage the disk for transparency. Then try a C&D, followed by a GS - but change provider lineup. Doesn't matter what to - deselect all, then select a single channel and try the call.
If that works, repeat, using your real provider lineup, and again, deselect all, followed by selecting a single channel. Once this succeeds (fingers crossed), then you can add channels back (via TWP is lightning fast).
If the first step fails, (I know this is a pain) see if you can take your TiVo to a mate's house. This will determine if it is something on your home network which is causing the issue. This setup method, works with 99% of all known TiVos with the AltEPG iso - so the only other possibility is that something on your network is causing an issue, or your isp is causing it (blocking ports?).