MacOS – What’s the most recent Mac that will run Leopard

No, this will not work. You can have multiple versions of OS X on one machine, but you can only install newer versions than the one that came pre-installed. For example, if your machine came with 10.6.4, you can't run 10.6.3 or older.

When Apple releases new hardware, the drivers for that hardware get rolled into a special build of OS X that comes only on that model. They don't get added to OS X in general until the next point release. (That means that drivers for the hypothetical machine I'm talking about wouldn't be added until 10.6.5.)

Apple doesn't release drivers as standalone software, which effectively makes it impossible to install and older version of OS X than what your Mac shipped with. You'll find that if you put the install disc for an older version in the drive, it either won't boot or it will refuse to install.

However, you can go the other direction. If you have an old Mac running 10.5, you can use Disk Utility to make another partition (HFS+ Journaled), then boot the install DVD for 10.6 and install it to that partition. To switch between the two after installing, hold alt when you boot up. (You can also select the default boot partition through the Startup Drive pane in System Preferences within either OS X install.) Boot camp is not required for this. Boot camp is only required for installing non-Apple operating systems like Windows and Linux.

First:

• consult the Utilities -> Console.app and check your logfiles, for some idea. ;)

Next:

• Activity Monitor (also in Utilities) may help shed some light and can tell you what code Finder is busy with and what else is happening at the same time.

  1. Look over the routines when you sample the Finder to see if they make any sense (or at least Finder gets caught in the same code each time to know you have one cause and not many)
  2. What processes are also getting CPU when this happens?
  3. Does this happen when all networks are disconnected?
  4. Are disk activity and network levels higher or lower than normal when this happens?

If Console does not help, you can trace all the network and file usage to see if you can snoop at what Finder and the system is doing:

• open Terminal.app
• in its preferences change the scroll-back buffer to 10.000+ lines
• and enter the next command
• sudo fs_usage #you will need enter the admin password
• after a while (10-20 seconds) you can interrupt with CTRL+c
• now scroll back and try get some idea - i understand than it is hard, because you will got hundreds lines what are normal...

This will show what files are currently used in the whole OS - maybe you will get some idea, what's happening.

maybe:

• HDD error in several sectors - (try check smart-status for your HDD)
• bad QuickLook plugin?
• remote HDD (iDisk?) timeouts?

UPDATE:

First - if your wife's account is OK - thats can mean,

1. the problem is "somewhere" bellow your $HOME dir, so it is probably not in /System or /Library, or
2. the problem is "somewhere" in /System or /Library, but caused by your login (StartupItem or LaunchDaemon or some your Preference setting what use Finder for some work - for example TimeMachine)

Some guessing (but honestly - these are not "advices" only pure guessing)

• uninstall PathFinder.

• check $HOME/Library/QuickLook folder. if anything is here, try move into ~/Desktop (for temporary) and relog - if not help, move them back - your should relog when moving plugins.

• check /Library/QuickLook (let there here only QBQL.., iWork) - don't trash them, only temporary move to desktop and relog.

• do you installed any Finder-plugin/hack - something?

• try disable TimeMachine - if it is enabled

• try eject (umount) all networked drives, and usb drives

• have you BootCamp especially with NTFS? - Try exclude it from Spotlight, TimeMachine etc...

• try exclude everything from Spotlight (this probably will not help, but for "sure" - your mdworder should stop indexing) (in the SysytemPrefs -> Spotlight -> Privacy - add your whole hdd and bootcamp too.)

• disable all sharing (SysPrefs->Sharing)

• download Onyx and remove all Caches. (this will cause increased CPU usage while rebuild cache again, but only for short time)

• remove ALL .DS_Store (hidden) files - don't worry, they're not essential. Sure exists some GUI tool for this job. If don't find any, you can try this Terminal command.

  find "$HOME" -name .DS_Store -print0 | xargs -0 echo
  

the above is for "dry run" - you can check what will be removed, if satisfied, change the echo to rm

• if none of above help (and probably will not :=() have no idea...

bmike? any other idea?