I have three problems

  Here is he story: I had to re install windows recently. After installing all of the drivers (some I got from dell.com) I've encountered three problems. Hopefully, it will be only one answer. One of the problems is that My memory ram fills up fast, even without doing anything, which makes me restart it ever so often. This takes me to the second problem Every time I try to log out, restart, or shut down my computer it shuts down the taskbar and the icons, but it freezes right there and only the wallpaper shows. Finally, if I try to connect to any wireless modem with a password it wont do it. I am running Windows  XP.