WordPress Plugin – Automatic Upgrade/ how to roll back to WordPress 2.6.5

HELP!!! I need to install Random Ad / Adserve for revenue from my site ( / ( ) , and since i’m too lazy, like many others, I use WordPress Automatic Upgrade! About an hour ago, I updated to WordPress 2.7, I just put folder with Random Ad on the website via my FTP client, then I went to Firefox (3.0.4, not beta, always updated!) to refresh, and guess what, nothing showed up! I deleted the folder and from the new dashboard plugin install thing i selected the file then clicked ok “Install Now”. It gave me the following error:

Fatal error: Cannot redeclare pclziputilpathreduction() (previously declared in /home/vladeekc/public_html/vs/wp-content/plugins/wordpress-automatic-upgrade/lib/pclzip.lib.php:5421) in /home/vladeekc/public_html/vs/wp-admin/includes/class-pclzip.php on line 5498

What in Windows vista does “pclziputilpathreduction” mean and how do I fix this? The website is working just fine, and how do I Downgrade back to WordPress 2.6, or just reinstall 2.7! Please Help!