It's a QuickTime program file rather than an iTunes one. (iTunes uses QuickTime for audio and video playback.)
When you did your reinstall, was it just of iTunes? Or did you do related software components too, as per the following document?
[Removing and reinstalling iTunes, QuickTime, and other software components for Windows Vista or Windows 7|http://support.apple.com/kb/HT1923]
I have discovered the reason this occurs. It is because the PATH in the environment settings no longer has the path to C:\Program Files (x86)\QuickTime\QTSystem which is where the .dll lives on a Windows 7 computer. Close the application giving you this warning if it is still open and use the following 10-step process to fix this:
1. Search for the path to the QTCF.dll and upon finding it, copy it (Highlight it in the explorer address bar and press CTRL + C.)
2. Open the control panel.
3. Choose System and Security from the left.
4. Choose Advanced system settings from the left and a dialog window pops up with the Advanced tab selected.
5. Click the Environmental Variables... button near the bottom of the dialog box.
(This opens a dialog box with 2 sections: User variables and System variables.)
6. Scroll down through the System variables section so that you can select (highlight) the Path variable in the left column.
7. Click the Edit... button which opens a small dialog box and highlights the entire Variable value.
8. Click once in the Variable value (to deselect the value so you don't mess it up) and then press the end key on your keyboard (to move your cursor to the last character of the very very long string in the text box).
9. Paste (keyboard combination CTRL + V) the path to the QTCF.dll you copied earlier, and add a semi-colon, for example:
C:\Program Files (x86)\QuickTime\QTSystem;
(Note that you don't need a trailing / or the actual .dll name in the path, but be sure to add a semicolon to the end of the path name you paste.)
10. Click OK on each of the 3 open dialog boxes.
There is no need to reboot your computer. You only need to restart the application and ensure that it starts without the warning that the .dll can not be found.
2 1/2 years after you posted it this thread is still helping people.
After a fresh install of Windows and Adobe Premiere Pro I encountered this problem, bearing in mind that over the course of the last 2-3 years I've repeated this process several times and not had a problem. All I had to do is add in the ; mentioned in point 9 above. I'll admit I was sceptical, but it worked a treat.
Thanks for sharing!