These messages you are seeing when you hover over the green ticks shown in Webmaster Tools -> Crawl -> Crawl Errors are the standard messages explaining what kind of error would this sub-section of Crawl Errors report on. If there was a problem, you would have a red x and not a green tick.
Therefore as long as you have green tick in there, there is nothing to worry about!
Thank you for answering this. Good to know that everything OK. A bit misleading on WMT with message it provides, and also that it seems to be checking when on hover before it shows the message text. It would be a better message to say 'Everything OK'- anyway thanks for the reply - appreciated