Okay, I'm not an expert by any stretch but I've had a few similiar experiences. Please ignore any patronising pointers.

Problem 1: Do you run Windows? if so do you have a speaker icon in the lower right of the screen in the taskbar? right click the icon and select open volume controls Make sure that the volume level is not completly lowered and that mute is not selected.

Problem 2: Problems logging in are usually due to cookie settings in tools. What browser do you use? also, what's the web url? I could give it a go see what happens.