My apologies. I forgot to mention I'd tried these steps in that KB.
For step 1, there were no .bak entries, and resetting RefCount etc had no impact
For step 2 doesn't apply as I was able to create a new bare admin account that exhibited the same problems, the issue isn't isolated to one login, therefore it isn't a SID corruption issue
For step 3 I did create a fresh new profile that exhibits the same problems (on first log in only, see below).
It seems to be services related, like the user login and event services aren't starting promptly. I checked they are both set to Automatic.
The symptoms are:
- first login with either account gets the error message, and a bare desktop ("creating desktop....")
- log off that account, then second login with the other or same account works fine (presumably services have started up by then)
Basically the 2nd login from cold boot with either account is always successful.
Just now, I was able to cold boot and log in first time, no issues, though this has only happened once in the last week.