Briefly, I had played several hours, firing on all cylinders which is generally as usual.
Saved, exited and fiddled in the CK with my mod for a short time.
Try to restart, damn game now CTDs right as the Akatosh emblem
comes on. This reminded me very much of Oblivion with a bad mod, so I disable the
obvious suspect. Same, same. Installed 1.2.6 of the USP and BOSSed it. Same same.
Any insight, suggestions would be appreciated.

So you disabled the mod you fiddled with eh? Sounds like script issues.
Did you do a total clean uninstall of it? E.g. not only by disabling the esp/esm but removing all those files? The thing is, disabling or removing a mod sometimes cause more problems. Do you have the original mod that you didnt fiddle with?

And what is the mod called. Perhaps i can help you debug further

Well, while I was waiting for any possible replies, I tried the old disable them all trick. It seems my problem was with Expanded Towns & Cities 5.0. With its various parts disabled, my game fired right up. My own mod, which is mostly just price tweaks and a couple cheat rings isn't causing any belly aches at all. At this time. Thanks for your reply and offer of help.

Too bad about the other mod. It sounded like it might have been good.

I use Expanded Towns and Cities, no crashes over here and is very stable. I don't like it when people come here and damn a mod to Oblivion because they don't look after their mod order, clean mods, follow mods instructions and fiddle with mods on their current saves and then wonder why they have a CTD.

Crashing at loading screen sounds like you had a mod that was missing it's master file.

I had no problems with the mod expanded towns and cities myself I only uninstalled it because had issues with followers and npcs being stuck or act like a pinball effect that they try to follow me but they can't otherwise it's a great mod just need to fix some of the walls and other stuff.