ITunes refuses to open... and I've tried everything.

Question

Until tonight, iTunes had been functioning normally... and now it simply will not open, no matter what I do.
I've spent the past two hours going through every possible solution on both of the following pages:
http://support.apple.com/kb/TS1421
http://support.apple.com/kb/HT1926
...and it has had absolutely no effect. Trying to open iTunes produces nothing more than a momentary hourglass. The process opens in the task manager, but nothing else happens. Is there something somewhere that I may have missed that may still be corrupted? I've honestly deleted absolutely everything Apple off my computer, including all application data from all users and disabled all other services and start-up processes and installed from a clean reboot, and it still refuses to work.

Answer 1

Just to be clear where you are, when you try to start iTunes, do you see the hour glass briefly, then nothing.
If you open the task manager after attempting to open iTunes, can you see iTunes.exe running on the processes tab?
Which service pack are you on for XP and did you make any changes to your system before the problem started.
Which version of iTunes are you on and did the problem start after an upgrade or out of the blue?
Anyway assuming you have silent launch failure with persistent iTunes in the task manager, the problem is most commonly due to a problem with cryptographic services.
If it occurred out of the blue with no prior changes to your system, you need to do a full scan for malware with up to date definitions. Malware can interfere with cryptographic services and prevent a solution.
So ... before starting troubleshooting, you need to be certain your system is clean. You can get a second opinion from the Kaspersky free scan - it is good at finding things but doesn't remove them.
http://www.kaspersky.com/virusscanner
Also a quick thing to check is your smart card service, which iTunes needs to start.
To check, go to:
Start>>Run>>Services.msc.
Look for the smart card service, check that is present and not set to disabled. Mine is set to manual.
I will give you the rest of it after you have checked for malware.