Win 7 Boot Manager now appears ...

[pam123]

All this started abruptly when the start screen blanked without warning.
Pressing restart got the Win7 boot manager screen.

From there I press enter to select the normal start up screen and go to the log in , but my usual log in doesn't function.
I have to use an alternative log in and then " switch user" and log in that way.
Which begs the question of why that should work.

After that the computer functions without problem.

There is no malware and when I ran the Win 7 memory test there were no errors.
It could be the hard drive but the boot manager/no log in problem is, apparently the only one and I won't have time to do so this morning before I have to leave.

Any ideas gratefully received.

[EzyStvy]

Its possible the user profile is corrupt/getting corrupt. Might want to backup any important docs just in case.

[pam123]

I changed my log in and, guess what, no trouble when I booted the computer just now.
I don't trust it.
Back up starting later this evening.

[ChoboSeki]

You got the boot manager screen due to a bad shut down.

As far as the login not working, probably corruption due to locking up the first time.

No idea why you would get a blank screen unless there was corruption or bad config or bad hard drive / hard drive stop responding and/or another device stops responding (another hard drive or a PCI card for example)

[pam123]

Good call.
Something isn't shutting down like it should.
I think it's Steam but I'm checking further.