I am experimenting this problem deleting an IP restriction on IIS:
I have given all permissions to the user but it did not resolve the problem, I also try to free some space on disk without any result, is there anything that I can try to solve it, this is happening since a month ago, thanks beforehand for any help.

Try editing the file using notepad launched from an admin command prompt.
Open a cmd prompt by right clicking it, select 'run as administrator'.
At the cmd prompt type
notepad c:\windows\system32\inetsrv\config\applicationhost.config