Error "Unable to create this part due to an internal error. Reason for the failure: assertion failed: " in the Eclipse

I've met a bad errror in Eclipse 3.2: Unable to create this part due to an internal error. Reason for the failure: assertion failed:
But at last I've solved this problem,it might be caused by the synchronization of the updates, for example if you make a the latest update to Eclipse 3.2, but at the same time perhaps you can not use the plugin that you've installed successfully and then the error above may appear,another reason that i surmise is that two same files(such as *.java) in the build path that belongs to one workbench.

Two suggested way to resolve it:
1.make your eclipse and plugin update synchronous
2.save your project in another directory and delete it in your workbench, restart the eclipse and rebuild again, if it doesn't work, try method 1.