I have recently returned to a project after not using it for a couple of weeks. The project was not created in Eclipse it was imported, and there is no \'.classpath\' file in t
I had the same problem. I had just setup a new PC, I transferred my projects to the new PC, clicked on the workspace directory, and changed the permission so that I (the 'me' on my new PC) owned all the files in all all sub-directories. However, even after doing this, eclipse couldn't write to the .classpath files. I verified that I could write to them using notepad, and that worked fine. I also verified that the O/S knew I was really the owner, but it didn't help. I also tried running as admin, but that didn't help either.
Then I found this link: http://blog.ryanrampersad.com/2010/03/03/setting-build-path-has-encountered-a-problem-in-eclipse/, which indicates that when you copy files to a windows7 machine, windows may set the 'hidden' attribute on the file, and when this happens, eclipse can't work with it. I did a find files from the workspace directory, looking for '.project' (and subsequently '.classpath'), and selected all the files, right-clicked, and un-checked the 'hidden' attribute. This fixed my problem.