[I cannot log in to Second Life. I get the message that I cannot do it from my computer.]

I cannot log in to Second Life. I get the message that I cannot do it from my computer. Never happened before. Same computer since over a year. Latest SL Viewer

Comment from me, Sandon Galicia, several days later:

Thank you for your answers and trying to help me. I rebooted and restarted as I kindly was adviced to do. And I was back on track. I have had some minor disturbances with logging in after that but nothing like the first and kind of confusing message that popped up. 

Thank you for your help!