Mobile facebook virus, can rarely login?

Hi, I recieved a message on facebook. It was a youtube link to a video. I opened the message then realised that the sender had sent it to a load of other people with the same initial from their first name. Since then, most times when I try to login from my phone an icon saying "no response" shows up. The next day the girl who sent me the message posted a status update telling people she did not send any messages to anyone even though lots of people had recieved them and were now having problems with their facebook login.

What can I do? I'm pretty clueless about stuff like this! Thanks, Chris :)