I ran updates last Thursday. Since then, my Ubuntu 12.04 has been unable to log in successfully under my existing user sign-on.

I get the sign-on screen appear, I type in my password, then the screen goes black and ..... that's it. Where the desktop is meant to appear - nothing. However, the pointer arrow is still there, plus I can do Ctrl-Alt-F2 and drop to the shell, and list my home partition and do stuff there - but no GUI.

I should point out that I can log in successfully as a guest, and also that my login fails whether I log in as Unity 2D, 3D, OpenBox or LXDE (which I have installed as well). It just doesn't want to know.

Also, I don't use my home directory at /, I have set up a home partition. If I delete reference to this home partition in fstab, and revert back to the default home directory, it loads fine as well.

So I assume it is a problem with a config file in my existing home partition.

I have looked around various error and log files, and posted help pleas on other forums, but to no avail.

Can anyone suggest any config files stored in one's home directory, that could be either amended or deleted, that might rectify the situation?

Thank you for any help you can give.