Processing, Arduino and COM Ports

I started using Processing about a week ago. The ability to display a lot of the data in such attractive ways has been a huge bonus.

However when I try and quit the window, there is a persistent problem that keeps making things hard.

The window refuses to close properly so I sometimes have to use Task Manager to force it close. That's not a big deal.

When I try and open the display window again, it says the COM port is busy.
When I switch over to the Arduino IDE and try to upload a sketch, it says the COM port is busy.

If I replug the board, the name appears in the Device Manager but disappears from the list of Serial Ports in the Arduino IDE.
If I try to restart the display window in Processing, it says that the COM port isn't there.

The only solution I've found is to then upload the sketch to a new board but as soon as I use Processing, that board will undergo the same process and essentially be disabled.

The only way of 'restoring' all these boards is to restart the computer.
As you can imagine, restarting the computer after every run of Processing is tedious and there are only so many boards I can use in a single sitting.

What's wrong here?
What information should I provide to help you help me?