There is a known issue with Googlebot right now in which Googlebots are resetting TCP connections before the handshake completes. This causes the bot to not connect and will leave an error message in some customer’s Web Master Tools interface that look like this:
/*Fetch Failure: The resource was unable to be fetched for some other reason. In general, this happens when the resource is either explicitly blocked by the server (for example, this is the case with the Google Analytics scripts) or if Googlebot’s request times out without a proper response from the server. We use a shorter timeout for the Instant Previews testing tool than we would for normal requests to make these issues more visible and to improve the user-experience when interacting with this tool. */
This issue is know to Google and they investigating as indicated in this thread:
http://productforums.google.com/forum/#!topic/webmasters/mY75bBb3c3c
