12.04 LTS shutdown restart does not respond and login screen repeats.

[Newoldie]

I have a couple of things happening which I hope are linked and have one solution.
1.I was using Ubuntu Classic (the one without the sidebar?) but this stopped letting me login but did not give any message (unless I entered the wrong password where it gave the correct "try again").The screen would flick blank and then redisplay the login screen.
I could logon as guest and then run software update using my administator password.
By trial and error I found that if I select Ubuntu 2d and then enter my password I can logon.
2.The shut-down feature also stopped working.I get the shut-down options screen but clicking on restart or shut down has no effect.

I have not knowingly downloaded or altered anything and as the problems started at the same time I hope they are linked.
System updates appear to install without problems.

Thanks,Dave

[CaptainDangeax]

Hi.

Maybe you have a failure in your config files. Go to the console "CTRL + ALT + F1", save your data, and create a new user with "sudo useradd dave2". Give a try using the new login. If everything is OK, it's a profile issue. Deep clean your /home/dave, including hidden directories. Don't worry they will be recreated on next logon. If dave2 is still a mess, consider reinstalling everything and hope it's not hardware related.