\shell "Open with Application Issue" Issue?

I''ve got about 50 registry integrity issues of the form:

Problem: Open with application issue

Data: Applications\QuickTimePlayer.exe\shell

Key: HKCR\Applications\QuickTimePlayer.exe

In most cases the relevant application is still installed, and still working. Why do these keys come up? For example quicktime is installed at C:\Program Files\QuickTime\QuickTimePlayer.exe