We came across this problem today: Replies in Apple Mail app always show the same (wrong) sender date like "On 26.09.2007, at 14:08, Tom Jones wrote:" and its always 26.09.2007 in every reply to any sender, no matter on what date they had really sent their e-mail.

The solution to this is in System Preferences > International > Formats
Change the Region from "Custom" to your local Region e.g. "Switzerland"

Not so long ago I upgraded a 12" PowerBook from Tiger to Leopard OS X, resulting in a blue screen on restart right after installation.
The cause was the Unsanity Application Enhancer installed on the old system. If you do an upgrade, check if you have Application Enhancer (a helper Extension in System Preferences, used for Applications like Airfoil for example) installed and uninstall it if its there.

In case the blue screen is already there, help is provided on the Apple's Support Discussions:

http://discussions.apple.com/thread.jspa?threadID=1197402&tstart=45

Boot your blue screen Mac in Firewire-mode if possible (by pressing T on startup), connect to another computer and remove the following files:

/Library/Preference Panes/Application Enhancer.prefpane
/Library/Frameworks/Application Enhancer.framework
/System/Library/SystemConfiguration/Application Enhancer.bundle
/Library/Preferences/com.unsanity.ape.plist

If Firewire-mode doesn't work you may have to remove your hard disk and place it in an external drive to sort t out. For me Firewire-mode worked fine though.

If your Mac won't shut down, there's a big chance the problem lies with iDisk Sync being turned on (in System Preferences), - it can even cause problems in manual mode. It may also use up a large chunk of local disk space, because the system keeps a copy of your iDisk's contents.

We we're trying to connect to a Mac running OS X 10.5.1 from a Windows machine running XP over the network...
Following the instructions the Sharing Preference on our Mac gave us, we were without a chance.

OS X 10.5. suggests the following path: smb://10.0.1.9. - we got nothing but error messages on our Windows machine. I remembered in OS X 10.4. it used to be backslash, - and indeed, without the "smb" and using double-backslash instead of double-slash it works.

To avoid problems with routers blocking your connection, use a network (ethernet) cable to connect your mac and your PC directly.
- Switch off the AirPort on your MAC, for this will give you the wrong address in the Windows Sharing pane.

Why the hell do Apple tell us "Windows users can access your computer at smb://10.0.1.9." when this obviously doesn't work? Maybe I don't know enough about Windows (true!) and using this path somewhere other than in Run from Start Menu would work..?

However, the Sharing Preference Interface in OS X has gone from bad in 10.4 to worse in 10.5 - this is not what a Mac should be - which is to offer an intuitive and user friendly interface. Although it must be said, technically it has improved, for example by offering the long missed option to allow access to specific folders.

On Windows enter your Mac's address 10.0.1.7. in the Run app:

If you can't see the smb://... path in your Mac's Sharing Preference, remember to click "options" located bottom right in the sharing preferences window and select "Share files and folders using SMB" and deselect the AFP checkbox - this used to simply be "Windows Sharing" in 10.4 Tiger...

To configure your Mac so you can access more than just your shared folders from the PC, add whichever directory / folder you want by clicking on the plus below the Shared Folders pane in the Sharing Preference window (in my example this is the folder "Larne" - with you it might be the "Documents" folder. Then grant Read & Write access for yourself in the Users pane.

Troubleshooting: If you still can't connect, try...
- with your firewall on your Mac turned off (remember to turn it back on when you're done).
- try using a direct computer to computer ethernet cable connection instead of going through your wireless network.
- If you have a direct connection with a cable, make sure to turn off the AirPort on your MAC!

Apparently some people have problems sending files from their phones to their Mac under Leopard. There's a new item in the System Preferences under "Sharing" called "Bluetooth Sharing". This must be activated to accept files sent from phones.

My Apple, this is not so impressive... (From Heise Security) via MacRumors.com:
Leopard's firewall] is not activated by default and, even when activated, it does not behave as expected. Network connections to non-authorised services can still be established and even under the most restrictive setting, "Block all incoming connections," it allows access to system services from the internet.
Read on..