Ok, try to do that:
- First you have to totally uninstall iTunes, Quicktime, Apple Software updater...-anything with Apple in the name.
- Second, open regedit using "run as administrator".
- Then go to the registry key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UserData\ S-1-5-18\Components\25E80ACDE408FA340A7FB908F9CCEFFB\90F2D0AC118F4D8448E38C67696 C94A9D (this is the data I see in the screendumps)
...and selected the folder 25E80ACDE408FA340A7FB908F9CCEFFB
Right click & choose permissions
click advanced, and then the owner tab
type "administrators" in current owners field and check th box to replace the owner on subcontainer and volumes
Apply settings and then click permissions tab. Once again, add "administrators" to the list of permission entries, then click edit and check all permission boxes. Also click the 2 bottom boxes concerning the inheritable permissions.
Click OK
Now back on the main permissions tab, choose administrators in the group or user name window and then check full control and read checkboxes. Click OK.
Back in the main regedit window, you should now see keys in the right pane for each subfolder in:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UserData\ S-1-5-18\Components\25E80ACDE408FA340A7FB908F9CCEFFB
On the menu bar click file > exit
download and install the new combined iTunes and Quicktime from apple.
Everything should work fine. I hope this helps.