The entry point..

That one can be produced if you have an older version of Apple Application Support on the PC than is required by your current iTunes version. (The required version of Apple Application Support is included in the standard iTunes installers, but for some reason it hasn't been updating properly for some folks, for iTunes version 11.1.4.62 and possibly 11.1.5.5.)

Let's try updating your Apple Application Support to version 3.0.1 by doing a standalone Apple Application Support install.

Download and save a copy of the iTunesSetup.exe (or iTunes64setup.exe) installer file to your hard drive:

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

Download and install the free trial version of WinRAR:

http://www.rarlab.com/download.htm

Right-click the iTunesSetup.exe (or iTunes64Setup.exe), and select "Extract to iTunesSetup" (or "Extract to iTunes64Setup"). WinRAR will expand the contents of the file into a folder called "iTunesSetup" (or "iTunes64Setup").

Go into the folder and doubleclick the AppleApplicationSupport.msi to do a standalone AAS install.

Does it install properly for you? If so, can you launch iTunes without the error now?

If instead you get an error message during the install, let us know what it says. (Precise text, please.)

Okay. Instead try launching WinRAR. In WinRAR, browse to the iTunesSetup.exe (or iTunes64Setup.exe) you downloaded, select the file, and click "Extract to".