When apps install on a mac they leave an installation receipt in /Library/Receipts - typically anywhere between 40Kb and 5.4Mb (the latter for a QuickTime update). AR9, however, leaves a receipt that is 41Mb in size, which is coincidentally exactly the same size as its installer .pkg file. So the receipt is a copy of the installer it's a recipt of? Bizarre.
Mac OS 10.4.11: I could not open pdf docs today (12-24-08), uninstalled & installed Adobe Reader 9.0.0. pdf docs icons changed but open, however cannot open Reader from Applications and get: Adobe Reader
Then immediately get this error message:
Adobe Reader could not install correctly.
Adobe Reader was unable to install a necessary component
and must quit.