running itunes problem..

Unusual ... ASL.dll is an Apple Application Support dll. However, if it *really was* missing, after the ASL.dll is missing message I'd expect you to get an error 7 message, and iTunes wouldn't start.

By any chance, have you currently got a copy of *QuickTime Alternative* installed on the PC? The last time I checked (admittedly a few versions ago), that also installed a version of ASL.dll. It also changes QuickTime registry settings, which might mean the PC was currently "looking in the wrong place" for your ASL.dll. (That could plausibly produce the combo of the ASL.dll-missing message with the subsequent actual launch of iTunes.)

I think I might have installed QuickTimeInstaller.exe if that's what you meant by a QuickTime Alternative.

No, QuickTimeInstaller.exe sounds like a "real" QuickTime (assuming you got it from the Apple Website). That's the name of the standard QuickTime installer. If you had QuickTime Alternative installed, you'd likely see an entry "QuickTime Alternative" or "QT Alternative" appearing in your Uninstall a program control panel.

The pop up also appear after I turn on the computer, I have to close it a few times before it stop popping up.

... that's also consistent with trouble with AAS. The iTunesHelper.exe background process uses Apple Application Support. The process runs on startup by default, so if AAS is missing or damaged, the iTunesHelper process (and possibly a few other processes) will throw error messages at you on startup.

and for the folder which I move from SysWOW64 to the desktop (QuickTime.cpl and the QuickTime folder) is it ok to delete them? and about the missing QuickTime.qtp?

Yes it should be safe to delete those now. The precise files and folders that get installed on the PC differ from application to application, so there may have been no stray QuickTime.qtp in the SysWOW64.

After the deletions, try restarting the PC again. Do you get another set of error messages this time?

Okay ... although it's an atypical sort of case of an ASL.dll problem, I think we'd (eventually) better try swapping out your Apple Application Support and your QuickTime. We'll take a few explicit precautions away as well, just in case.

Doublechecking something before proceeding ... do you currently have Safari for Windows *version 5.0.1* installed on the PC? (If so, we'll have to adjust our strategy accordingly, because 5.0.1 needs a higher version of AAS than is contained currently in the QuickTime and iTunes installers ... not a huge deal, but we need to plan ahead for it to save us some additional uninstalling/reinstalling later on.)

Good-o. Let's try moving forwards. Best to print out 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 QuickTimeInstaller.exe file to your hard drive. Don't run the install on line and don't start the install just yet. Get the installer which doesn't mention itunes:

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

If open, close all of iTunes, QuickTime and/or the MobileMe control panel. (Since all use AAS they can all interfere with the QuickTime/AAS uninstalls if open, and QuickTime could interfere with its own uninstall.)

*Uninstall phase*

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

(From this point on until we get AAS and QuickTime reinstalled, iTunes won't run (because it uses both other programs) and the MobileMe Control panel won't run (because it uses AAS).)

Next we'll remove any leftover program files and folders.

In Computer, open your C drive or whichever drive your program files are installed on.
Open the "Program Fiiles (x86)" folder.
Right-click on the "QuickTime" folder (if it still exists) and select Delete.
*Staying in "Program files (x86)",* open the Common Files folder.
Open the "Apple" folder.
Right-click on the *Apple Application Support* folder (if it still exists) and select "Delete".
Go back out into Computer.
Open the C drive or whichever drive your operating system is installed on.
Open the "Windows" folder.
Open the "SysWOW64" folder.
Right-click on the QuickTime.qts file and the QuickTimeVR.qtx file (if they still exist) and select "Delete".
Empty your recycle bin.

*Reinstall phase*

Restart the PC. After the PC restarts, you'll get another bunch of error messages from iTuneshelper and other background processes. Click through those. Do not open any applications after the PC starts.

Disconnect from your network and/or the internet. Now switch off all your security software (firewall, antivirus, antispyware).

Now start the QuickTime reinstall by doubleclicking the QuickTimeInstaller.exe you downloaded earlier. (This should reinstall Apple Application Support, too.)

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

Did the install seem to go through okay? If so, restart the PC. Do you still get the error messages on restart? If not, how about when launching iTunes?

🙂 Excellent news! Glad you're up and running again.