Xcode cannot save file

I am on Mac OS X 10.6.8 using Xcode 4 with Cocos2D.

The other day, I got an error message out of the blue when trying to run my project:

The document "MainMenuScene.m" could not be saved.

I tried the following, none of which has worked:

• replacing the file
• creating a new one and renaming it (which I could not rename it. I was told I didn't have permission)
• creating a whole new project and reading the files/copy pasting the code in
• opening Disk Utilities and running Repair Risk Permissions (which works again once, but then reverts back).

I sometimes get the off chance and the file does save, but reverts back to not saving again.

Anyone have any ideas on what I can do to fix this?

See the full conversation in the comments, but this ended up being solved. Moving what was suggested/asked here for clarity and closure.

Is that the full error? Also, are you saving it on a USB or your HD?

Are you an admin on your computer, etc? Have you tried to move the project completely, or copy and try to work on it from somewhere else? With the currently given information I cant think of anything that would cause that kind of problem. What has changed since you were last able to edit and save without issues?

Glad we got it figured out!

-Karoly