New games and applications don't work

hello, so I've got a question:

If I download a new application or a game to my computer, it almost always won't work. How is this possible

Can you give us some examples of the games that aren't working?

Just some small games from the web. That's not the problem, but the applications, really.. Limewire, torrent applications etc.. also my flash player lags very much. I can't watch any videos on the web, it's like still pictures.

My whole computer lags a bit.

Why don't you provide some specifics on your machine so we can try to help you out?

Like the year, model, how much memory do you have, how hard drive space left, and so forth....

Regards.

My guess? You probably didn't drag the file from the disk image to your applications folder. So your computer is reading it as though it is data off of a disc.