Don't fret peeps. Square has taken note of the issue (a short time after this thread started) and they're trying to fix it as we speak. Here's a post from the site that's a little reassuring:
From:PlayOnline
Dec. 13, 2005 05:20 [PST]
PlayOnline Viewer Technical Difficulties (Dec. 13)
Currently we are experiencing technical difficulties with PlayOnline Viewer (Windows version only). The issue is currently being addressed, and new updates will follow as additional information becomes available.
We apologize for the inconvenience.
[Date & Time]
From Dec. 13, 2005 03:30(PST)
[Details]
-PlayOnline Viewer would shut down upon login.
[Affected Services]
PlayOnline (Windows version)
http://www.playonline.com/ff11us/polnews/news6259.shtml So...if there's anything else that might need doing, might as well try, because reinstalling anything (or everything) is probably just a waste of your time, and dangerous to your comp (as a few posters have noted). Let's all wish SE good luck and godspeed on getting this fixed! ;_;