How are you enabling/disabling the root user? Through Directory Utility?
I do remember seeing some problems with logging in as root more than once in early Lion releases, but assumed it had been fixed. Try searching the forum for more on that.
Meanwhile, you can always get into root via Terminal if you don't need the GUI. In Terminal, type
press 'return', enter
press 'return' again and type in the password and one more 'return'.
Where is the folder you wish to change the icon for?
Are you trying to just change an icon for a single folder, or are you trying to change the default icon on a system folder?
Either way, I don't think you need root access to do it. At the very least it would be easier to sudo chown in the terminal to you, make changes, then sudo chown to whatever the ownership was.
If you are trying to paste an icon onto the image in Get Info, it won't work. You get the same type as the thing you are pasting. You have to paste an image onto that drop zone in Get Info.
I had an icon on it and then I migrated my computer to a new MacBook Pro retina and the icon reverted. I have a folder with the same icon and I tried copy and pasting over and that didn't work. I tried copying over the Icon file, but that didn't work either.
I'm sure I can find other ways of doing that, but I'm concerned about the odd behavior of not being able to log in as root regardless :-/
What Barney said is valid. There are other ways to accomplish an icon change. Terminal is also available. I also know the irritation of not being able to do something on your very own puter when you should be able to. (logging in as root, for instance)
Look at this thread. Seems to be same problem as you. Read both pages before you do anything as you do not want to make a mistake within Terminal or Directory Utility as apparently some posters did. Several solutions are available throughout the thread. Backups at times like this are always good as some risk is most certainly there.
You shouldn't need root to do that, but you must actually copy the image, not the icon or the folder. If you Get Info on the one you want, try copying the image in the Preview and drop that in the icon drop zone for the one you want to change. None of the problems you see are attributable to permissions, but how the icon image is managed. If you drop an icon file on the drop zone, all you get is the standard icon of an icon file, not the icon in the file itself. I think in previous systems, it worked as you expect, but somewhere along the line it changed.
I managed to copy the badge from my Sites folder onto the Webserver Documents folder using the copy from one Get Info and paste to the other. It asked for an authentication.
You have to copy and paste an image onto that spot in Get Info. You should also be able to copy the badge from one folder's Get Info window and Paste it into the badge of the destination Get Info window. Sometimes you have to copy the Preview Image
Seems to me not being able to log in as root is a benefit, not a problem. Unless other problems appear.
I do have admin priviledges. Reparing only resulted in the following and it still doesn't work.
Repairing permissions for “Macintosh HD”
User differs on “Applications/.DS_Store”; should be 0; user is 501.
Permissions differ on “Applications/.DS_Store”; should be -rw-rw-r-- ; they are -rw-r--r-- .
Group differs on “Library/Preferences/com.apple.alf.plist”; should be 80; group is 0.
Permissions differ on “usr/share/zoneinfo/America/New_York”; should be -rw-r--r-- ; they are -rwxr-xr-x .
Permissions repair complete