How do I handle an "Eclipse error while reading from repository" caused by a corrupted repository index?

Try refreshing the repository in Eclipse. Go to 'Help' -> 'Install New Software...' and then manage the repositories from the 'Available Software Sites' window. Select the problematic repository and click 'Refresh'. If that doesn't work, try disabling and then re-enabling the repository. As a last resort, you could delete the repository and then re-add it.