Wallet BUST

Hi guys, anyone else experiencing this?

Wallet been fine until today, now when mining, it randomly closes...usually after 30-40 mins, no erros ,i just notice window has gone, and when i hover over icon (notification area) it goes.
I re-open, and start mining again, no issues, but then again 30-40 mins in, same again, been like it all day.
No previous problems....has something been updated?
J