First I'll cover the things I don't know. Closing ports. I have never had the need to do that so I can't answer that question. My son always took care of that for me when he set up my system.
The icons at the bottom of your screen ..... are these inside the toolbar at the bottom or just above that. If they are in the toolbar are they in the quick access area or the active programs area?
If in the active programs area it will mean those programs are active and will take up more internal memory slowing down your computer. You can exit those that are not needed by left clicking on them and clicking on exit. If they are in the quick access area it doesn't hurt to leave them there.
Windows installer ...... a new copy of that can be received on the Microsoft update web site. If you go to their site and attempt to check for updates their system will automatically check the installer to see if it is a valid copy and should update it automatically if it isn't.
Without actually seeing your computer firsthand I can't be sure that your problem is fixed. You could probably check it by temporarily turning automatic updates back on for a short while. I would go to the updates site first though and do a check for updates function.
In case you don't have it the link is here:
http://update.microsoft.com/windowsupdate/v6/default.aspx?ln=en-us