A quick blog post to record the fix to this.
This issue effectively came out of nowhere. I headed off to lunch, and then came back and updated my local working copy of the code with SVN. Then all my projects in NetBeans (v6.8) turned red. Right clicking on them gave me the option to ‘Resolve dependency issues…’.
The next dialog told me that the library ‘junit_4’ was missing and needed to be added.
After much searching around, including advice to uninstall my NetBeans, I decided just to create a new library ‘junit_4’, and leave it empty. Lo and behold it worked.
Not sure if this is the correct fix or not, but all my projects have returned to that nice black colour again!