My eclipse installation was throwing some odd errors when doing basic things, like closing files...most irritating, so I tried the only two things I knew how to without conducting some google based investigations! the first is really the common sense first step which was to check for updates to my build and the various plugins I have installed, this gave no joy...I was still getting the silly errors. Next up was to run the -clean statement, I've not been unlucky enough to find anything that this can't fix yet and am happy to say it fixed these errors too.

So, how to use this comand? (it should be noted that I run Ubuntu Linux, these steps will be slightly different for windows/mac i'd imagine) Basically if eclipse is on your path,you can simply call eclipse -clean in the terminal and off you go, the startup takes a little longer than normal but it clears out your whole workspace of all the data thats built up installing stuff, updating stuff and also just the general mess that gets caused with heavy use. In my case, I didn't have eclipse available in that manner so I opted for my preferred method as below:

1. Open the terminal and type locate eclipse.ini, this returns the location of the file you want.
2. Type nano eclipse.ini to edit the file with nano(funnily enough!) and add the -clean statement to the first line, save and close the file then start up eclipse again, the startup time will be a bit longer but thats just eclipse doing it's thing.
3. Remember to edit eclipse.ini and remove -clean , you dont need to do this that often and it's not much to remember!

Hope this helps someone, like I said, I've not found anything (yet!) that the -clean statement doesn't fix and it's a good first or second step to try before getting into the guts of the matter and starting to think about a re-install.