Logging the putty session may offer some clue as to what is happening. See here for example:
https://my.kualo.com/uk/knowledgebas...=0&article=888
Sorry, scrub that, head not in gear. You really need to see the server side log, which of course you can't. (You could if you set up emailing from your RPi, but that's not something most people would want to do).
Before attemptiing to make a connection via Putty, pick the "default session" first. See 2nd screen shot here:
http://www.viktorious.nl/2013/01/14/...ession-output/
Highlight "default session" and click load button before entering ip of your RPi and clicking on open.

