This is one of those things that took far too long to figure out so I figure I’d save some people the headache. Running computer janitor on Ubuntu 8.04 will remove AIR (v. 1.5 at the time of this writing) if you have it installed, but you cannot simply reinstall the AIR package. You might get something like “Error 1″ or “An error occurred while installing Adobe AIR. Installation may not be allowed by your administrator. Please contact your administrator.”

The reason is because computer janitor removes the adobeair package while corrupting the adobe-certs package. Run the commands below to fix, but as a disclaimer, my ~/.appdata and ~/.adobe directories had nothing important in them. I’m not sure if AIR holds application data in either, so you might want to back it up first.

1. Open synaptic package manager and remove the adobeair and adobe-certs packages if they exist.
2. Delete anything to do with AIR: sudo rm -rf /opt/Adobe\ AIR/ /var/opt/Adobe\ AIR/ ~/.adobe/ ~/.appdata/
3. At this point you can do a sudo dpkg -l | grep "Adobe" and if you still see the adobe-certs package, run sudo dpkg --purge adobe-certs
4. Close your browser and sudo ./AdobeAIRInstaller.bin to reinstall.