The top issues are software problems. You should try to reinstall or update your audio drivers and make them all default values to start with. As for the losing the ability to type or browse, that's usually an issue with windows loosing focus, meaning that the window you are looking at/working on is no longer considered the primary window. If you have multiple windows open you can try closing all but the one you are using. Like if you have an excel spread sheet open in the background and are browsing the internet for some reason windows changes focus to the other one. You can also try looking at the task manager page to see what might be grabbing the focus. Sometimes it's a background program running, like anti-spyware and stuff that for some reason just takes the focus away from what you're doing.
As for the power button??? Every time you turn it off, no matter how you do it, it causes stress on the components. If you are skipping closing windows first and letting it turn off the computer for you than you are messing up the windows operating system - might be the cause of your other problems. You should let windows shut down before powering down. Windows needs to shut down its' programs in a certain order for them to start up properly when you turn your computer back on. I don't recommend you turning it off this way. Even though there's usually a 5 second delay for windows to do an emergency shut down when you push the power button it doesn't allow it to shut down properly, hence, causing problems down the road.