Problem with Windows Live Mail and cursor hopping!

I have a Sony laptop with windows 7, no problems to date until yesterday. When I am typing (including now typing this) the cursor hops back and overtypes and inserts into has been typed already. I correct the text and do another bit and then it happens all over again. Very frustrating. Does anybody have any solutions?

Also, I use windows live mail to access my email. A couple of times a week it downloads every single email that I have received since I first bought the laptop in early 2010 - we are talking thousands - not a major problem but nevertheless I have to delete them from the Inbox and from the Deleted Items Box each time. Another problem that has started is that Windows Live Mail won't accept my password - I have to shut down the application and open it again, also turn on and off the modem a couple of times and finally I can get in to read my emails.

I would be grateful if somebody could help. Thanks