Is your Outlook connected to an Exchange Server (e.g. in Office) or on a standalone computer? Your problem sounds pretty random to me.

You can try to start Outlook once with the command line (Start -> Run) with "outlook /cleanviews", this command will clean up your custom views.

I am connected to an Exchange Server.

I just tried the cleanviews switch. Of course, now I have lost all the custom views in all the folders - Calendars, Journal, etc - which were OK. Any way I can get those back now?

Do you think by cleaning out all the old custom views, that now when I set them all up again, they should be OK?