"Computer Not Authorized" for Apps/Songs Solution

My post is actually being written AFTER I solved a really strange problem with my iTunes account, which I got after receiving and registering on it, my iPad2 (possibly unrelated, but I mention it just the same). The support tech representative who helped me, Ryan, deserves full praise for the solution.

If suddenly certain songs, not ALL songs, you purchased with the SAME Apple ID as you always have had, or apps you need to update, launch a pop up saying you need to purchase them again, do this (4th item down on link below).

http://support.apple.com/kb/TS1389?viewlocale=en_US

Namely, REMOVE THE SC INFO FOLDER. According to the tech rep, it solves a conflict suddenly happening in iTunes Preferences.

The first step he had me do, which did not work, was to de-authorise my computer twice, then click on the troublesome song, which launches a pop up asking you for your ID password. That, theoretically should authorise your computer and you should hear the song. But, as I say, it didn't work. So if you have the same problem as I do, please read the link above carefully, back up the SC Info folder if you want to (I didn't), and then delete it. Restart computer, click on offending song, input password, and the song should begin to play automatically, again.

What a nightmare it was figuring what went wrong. I hope this info can be of help to another lost soul in future. Good luck!