Laptop - Windows 7 - Windows Live Mail

When I go to my e-mails I am getting a pop up window containing the above error message.  

The emails that I can see listed are accessible as normal and I can send e-mails. However my inbox has not updated for the last couple of days.

My smart phone and tablet which are synced to WLM have also stopped receiving - They use Android 'Jelly Bean' as the O/S

Oddly my tired old desktop which is also sync'd to WLM is running XP is happily updating and send/receiving via Outlook.com.

I have seen numerous references to this exact error across the web and there are suggested fixes which usually included deleting the e-mail address and then re cresting it. However I don;t to do thid in case I lose vital data. In any case these 'fixes'apparently work for some but not others.

I had this issue a few weeks ago and after changing my password a few times it seemed to go away. However it's back and this time the 'pasword change fix' hasn't worked,

Please help as this is extremely frustrating.