Hi
I think you will have to get back to square one. And for that you need your initial installation CDs
First follow this to uninstall A8 completely:
http://go.adobe.com/kb/ts_kb400658_en-usThen download the update that you want from here, if you don't want to upgrade to 8.2 only select 8.1 and then disable automatic update in preferences:
http://www.adobe.com/support/downloads/product.jsp?product=1&platform=WindowsYou should install at least 8.1 as this fixes quite a few issues.
hth
capt.