iTunes and Windows 7 64 bit

"The iTunes application could not be opened. An unknown error occurred (-50)."

I suspect a broken Apple Application Support when I see that one, bo. I've tweaked the following set of instructions for your 64-bit system. (Some program file locations and the names of the installers are different than on 32-bit systems.)

We'll try uninstalling/reinstalling both Apple Application Support and iTunes this time around, taking a few other explicit precautions just in case. Best to print off a copy of these instructions, because at one stage of proceedings you won't be able to use a web browser.

Preliminaries

Download and save a fresh copy of the iTunes64Setup.exe (64-bit installer file) to your Hard drive. (Don't run the install on line, and don't start the uninstall just yet.)

http://www.apple.com/itunes/download/

Quit any recent version of the QuickTime Player, Safari for Windows and/or the MobileMe Control Panel for Windows if you have them installed and open. (They all use Apple Application Support, and may interfere with the AAS uninstall if they are open.)

*Uninstall Phase*

Head into your "Uninstall a program" control panel. Uninstall iTunes. Uninstall Apple Application Support.

(From this point onwards, recent versions of QuickTime, Safari and the MobileMe Control panel will not launch, until we get AAS reinstalled by reinstalling iTunes.)

Next we'll remove any left-over program files and folders.

In "Computer" open "Local Disk C:" (or whichever drive you have your program files installed on).
Open the "Program Files" folder.
Right-click on the "iTunes" folder (if it still exists) and select "Delete".
Go back into "Local Disk C:" (or whichever drive you have your program files installed on).
Open the "Program Files (x86)" folder.
Right-click on the "iTunes" folder (if it still exists) and select "Delete".
*Staying in the "Program Files (x86)" folder,* open the "Common Files" folder.
Open the "Apple" folder.
Right-click on the "Apple Application Support" folder (if it still exists) and select "Delete".
Empty your Recycle Bin.

*Reinstall Phase*

Restart the PC. After the PC restarts do not open any applications. Disconnect from your network and/or the internet. Now switch off all your security software (firewall, antivirus, antispyware).

Now start the reinstall by doubleclicking the iTunes64Setup.exe file you downloaded earlier. (This should also reinstall Apple Application Support.)

Reenable all security software prior to reconnecting to your network and/or the internet.

Did the reinstall seem to go through properly? If so, does iTunes launch properly for you now?

Interesting ... perhaps try the *Verifying that Key Firewall and IPsec Services are Working* section from the following document:

[Tools and Procedures Used to Troubleshoot Windows Firewall|http://technet.microsoft.com/en-us/library/cc749386(WS.10).aspx]

Are any of the services disabled for you at the moment, bo?

Okay.

Just doublechcking something further. When you're turning Windows Firewall off, as per:

http://windows.microsoft.com/en-US/windows7/Understanding-Windows-Firewall-setti ngs

... is the trouble that the "Turn off Windows firewall" options can't be selected? Or are you able to select them, but when you click OK the Firewall stays on?

(Trying to see if narrowing in on the symptoms can give us a leg-up with searching for solutions to the issue.)

Good lord. So when you, say, do:

Open Windows Firewall by clicking the Start button , and then clicking Control Panel. In the search box, type firewall, and then click Windows Firewall

... the Firewall screen isn't coming up at all?

Are your other control panels opening properly in there? Or is it just the firewall giving you trouble?

I see ... it's not letting us get through to the next screen where the firewall-turning-off controls live.

Hmmm. Some research indicates that the effect of turning off the IPSec policy agent service on a PC should only prevent remote management of the Windows Firewall:

http://wiki.blackviper.com/wiki/IPsecPolicyAgent

But I think we'd better check to see what happens if we start the service, just in case.

If you start the IPSec policy agent in your Services screen, does that 'Turn Windows Firewall on or off' link start taking you through to the next screen?

(Mutter mutter) Let's get back to the firewall, then. Some investigations as to what we can actually do in there at the moment.

Rather than the "Turn iTunes on or off" screen, does the link up the top about "Allow a program or feature through Windows Firewall" get you through to the next screen?

If so, are iTunes and BonJour listed in the screen? If so, do they have checks next to them?

(Wondering if we're getting some non-standard version of Firewall suppression of iTunes launch here. Usually those errors are error-message-free ... but with the strangeness going on with your Windows firewall, perhaps that strangeness extends to the type of launch problem.)