My laptop has been working fine for the last 2 weeks with me logged in on F2 and running startx and the Mrs logged in on F3 and ran startx -- :1.0, we switch by pressing ctrl-alt-f7/f8 as required.

Today I came home and accidentally logged her out from Gnome and now when she tries to startx -- :1.0 from f3 Gnome just shows a greyish screen with a X which responds to mouse movements but the Gnome screen doesn't come up.

I have tried deleting with the .Xauthority files in her home and also mine but it doesn't help.

Both users can startx if another is not using X, but I can't get the F7/F8 switching going again.

If I ctrl-alt-F3 back while her screen is hanging I see
I have read a lot of pages that recommend deleting various .ICE authority and /tmp files but I am not too comfortable deleting stuff until I am sure I don't need it

Thanks for any help/ideas about this

Have you tried a different number? Try:

startx -- :2
instead

Sorry to take so long to reply the solution was to run

startx -- :1

and NOT

startx -- :1.0

I am a dumb@zz

Run xhost +localhost that may fix the problem.