If you are using Eclispe, maybe you will meet such error after you have installed a Eclipse plugin:
Error retrieving "feature.xml". [error in opening zip file]
When you open Help->Software Updates->Find and install to install a new plugin, this error will cause that you can not install the new one. What is the problem?
Do you remember how did you install the last Eclipse plugin? I guess you download the package and unzip or just put it into Eclipse's directory, without using the Software Updates tool in Help menu in Eclipse.
1. Delete the site.xml file in your Eclipse directory.
2. Run Help->Software Updates->Find and install, the error will not appear.
If the plugin has the official site, from where you can install it in Eclipse using Help->Software Updates->Find and install, I sugguest that you should not download it yourself and unzip it into your Eclipse directory.
For example, EclipseMe, you can refer to http://eclipseme.org/docs/installEclipseME.html to install it, otherwise you will meet such exception!
But if this plugin doesnt support online install, you can only download it and unpack it. But Good Luck!