MonoDevelop-Unity - Error while executing command

When I click in MonoDevelop on Help->Unity API Reference I get the following error:
Error while executing command: Unity API Reference

System.ComponentModel.Win32Exception (0x80004005): The system cannot find the file specified

Is there a solution to this problem? Does this happen to anyone else?
I already reinstalled Unity, but the error wasn’t fixed.

bump.

my scripting reference is located here: C:\Program Files (x86)\dev\3d\engine\Unity\Editor\Data\Documentation\Documentation\ScriptReference
and monodevelop in here:
C:\Program Files (x86)\dev\3d\engine\Unity\MonoDevelop\bin\

I have no idea why Monodevelop cannot find those files. Should the documentation be located somewhere else?
I have this issue on 2 different Win 7 64-Bit PCs (one is the german version and the other one uses the english (US) version of Win 7).

After restarting the computer a few times, the help navigates to Unity - Scripting API:
But it is not using the local help as described in the Roll-a-Ball tutorial.

I’m also having this problem. Running in Administrator mode didn’t help.

I noticed this today, and it only happens when I don’t have some text selected.