How do I stop my Mac from attempting Time Machine Backups? I have a 2005 PowerBook running 10.5.8 that, in its previous life, was my personal, full time machine that I used all the way through graduate school. It has been relegated to very light duty in the past year, and serves its purpose well. There is one minor annoyance that I'd like to get rid of, but have been unsuccessful so far. The problem is this: it is on most of the day, every day, and roughly twice per day I get a pop up window asking me to select a drive for Time Machine backups. Like I said, this used to be my full-time Mac, and I backed it up regularly so this seemed (at first) to be an artifact of its previous use/state. I do not need to back this machine up anymore and therefore do not need Time Machine on. I cannot get it to stop this behavior. Here is what I have done so far:


Solution: turn off Time Machine backups via System Prefs. Outcome: no dice. 
Solution: trash com.apple TM prefs file and restart the computer to reset TM to its default state. Outcome: no change. 
Solution: Create a new user account to see if the problem persists. Outcome: it persisted. 


So, I am out of solutions. This is a minor problem, as I simply dismiss the dialog box, but it is fairly annoying. Any takers?
If you're referring to the nag when you plug in a new disk, you can try the defaults setting mentioned here:

defaults write /Library/Preferences/com.apple.TimeMachine DoNotOfferNewDisksForBackup -bool YES


Alternatively, try decreasing the interval of backups to some insanely great number. Try the opposite of the setting listed as #26 on this page:

defaults write /System/Library/LaunchDaemons/com.apple.backupd-auto StartInterval -int 1800


You might try this to have TM prompt you once anually:

defaults write /System/Library/LaunchDaemons/com.apple.backupd-auto StartInterval -int 31449600


You might need to use sudo to apply these settings.