This error is something we do not get in any of our environments. Each Magento module is including a manifest-file. But if the manifest-file is good in our environments and bad in yours, than this might indicate a problem in your Magento site.
Could you please let us know the Magento version and PHP version you're using? Also, on which platform are you running this webserver (Linux, Windows, Mac)? Have you already tried installing other Magento modules using the same procedure in your Magento Downloader application?
I don't know exactly what you mean with trying to install 1 manually. Our GoogleGears module can not be installed manually. But if you tried to install another Magento module manually and you got the same problem, than this indicates that the problem is related to your Magento installation and not to our module.
We have tested this module with Magento 126.96.36.199, Magento 188.8.131.52 and Magento 1.4 - all work fine. If you haven't tried installing another Magento module just now, could you please do so and report back how this goes?
We tested the module thoroughly under various environments, but did not come up with the same error as you did. Most likely this problem is caused by third party extensions. To troubleshoot this, go to the Magento Admin Panel and browse to "System > Tools > Google Gears".
Next select the HTML-source in your browser and look for an URL which looks like this. Copy the exact same URL in your browser and post the output on this forum:
If you fail to connect to the Magento Connect server, that has nothing to do with our extension but with you and the Magento Connect server. If you have continuous problems, you should post your question on the Magento forum. We have tried ourselves and the extension installs fine. If you need more help and support, please contact us for custom support so we can make you a good offer.