"Trust this computer" message in iPhone 5 each time it's plugged, not recognized by iTunes

Question

iPhone 5 using iOS7 is not recognized by iTunes. It keeps popping up "Trust this computer" message each time I plug it in to my laptop (Windows 8). It shows in my devices in my computer. Both my iPad with Retina display and iPod touch 5th generation are recognized. I have followed instructions for this issue but not working, help!

Answer 1

I just wasted 2 hours of my life with this.  Finally figured it out.
If the above suggestion doesn't work (it did not work for me as the above poster completely failed to identify where to find this "MPT" and it was not listed in my device manager anywhere) .....
1)  Go to control panel > type Device Manager into your search box there
2)  Go down to "Portable Devices"  (the Apple help documents are a total fail on this one too as they say to look in "Cameras" after taking a "Screen shot" with the iPhone.  Did not work.)
3)  Inside Portable Devices you should see "Apple iPhone".  If you don't, expand every one of the Device Manager things until you find Apple iPhone listed.  Then ...
Then from the Apple support page:
For Windows Vista, Windows 7, or Windows 8
Right-click the Apple iPhone, Apple iPad, or Apple iPod entry in Device Manager and choose Update Driver from the shortcut menu.
Click "Browse my computer for driver software."
Click "Let me pick from a list of device drivers on my computer."
Click the Have Disk button. (If the Have Disk option is not present, choose a device category such as Mobile Phone or Storage Device if listed, and click next. The Have Disk button should then appear.)
In the "Install from Disk" dialog, click the Browse button.
Use this window to navigate to the following folder:
C:\Program Files\Common Files\Apple\Mobile Device Support\Drivers.
Double-click the "usbaapl" file. (This file will be called "usbaapl64" if you have a 64-bit version of Windows. If you don't see "usbaapl64" here, or if there is no Drivers folder, look in C:\Program Files (x86)\Common Files\Apple\Mobile Device Support\Drivers. instead).
Click OK in the "Install from Disk" dialog.
Click Next and finish the driver-installation steps. Open iTunes to verify that the device is recognized properly.
Once I browsed to that exact file and installed it, it worked.  iTunes popped up and loaded the phone.
Hope this helps someone.  There's *no reason* this should be happening.  This is a brand new iPhone 5s for me on Windows 8.  The Apple help files need to be corrected.