AirPort Signal Going On and Off


Mac Convert for Life
I've been using the same wireless ISP at the same locations since I bought this iBook (a few months ago). Never had any problems. Suddenly, for some reason, today my AirPort icon in my menu bar kept going on and off, thereby disconnecting me from my network. When I clicked on the AirPort icon, my regular network wasn't even on the list! So, I clicked on Other and typed in my network's name and tried to join that way. I got a message that popped up telling me that there was an error trying to join the network. Then, a few seconds later, I got another message telling me that my computer doesn't recognize any of the networks but would I like to join so-and-so network? Well, the so-and-so network IS my network! So, I clicked Yes. This process repeated several times today. I finally went to my Finder: username/Library/Preferences and trashed the AirPort plist. I restarted my computer and have not had that problem since.

1. Why did the problem occur in the first place?
2. Was the cesation of the problem mere coincidence, or did trashing the prefernce file likely solve the problem?