The Engineer in me is in Comatose

Few days ago, my PC went a little crazy.

It refuses to boot. Once.
Then it froze on me after a few minutes.
Then I didn't use it for a day.

The next day, it booted up, but I lost my wireless connection. The USB wireless adapter driver refused to load.
Unplugged and re-plugged it in. Doesn't get recognized.
Tested that the USB port is NOT faulty.
Removed the driver, and reinstalled the software - Still can't work.
So must be my Wireless adapter lah !

Next day, I brought a new one back.
Plugged it in, driver loaded, but just cannot connect to my router.
Did a search and saw many wireless networks around, including my router. Tried all configurations, passwords, encryption. Just refused to connect.
Reinstalled drivers.

Did a scandisk before trying to reinstall Windows XP. Many files with problem.
Installed Windows XP. Some file problems. Nevermind. Booted fine.
Now my anti-virus couldn't run, and I still cannot get my network connection.
My MS Outlook can't start ; MSN needs to be reinstalled.
Then realized I used the wrong version of Windows XP.

Found the right version, reinstalled Windows XP.
Still can't get wireless connected. MS Outlook runs ok, but not my Anti-virus. I was angry and was contemplating between buying a new notebook that I want and reformatting this PC.

Then suddenly, like a huge pair of king-kong hands, it hit me. On my cheeks and my head.
Went into the Router configuration, and updated the MAC Address Filter.
I got my wireless connection back ! *Grrrrrr*

So now everything is ok again.

Why didn't I think about that right at the beginning !?!?!?