Well, i recommend you that you change your server from Microsoft Web Server to a more approriate server for php, such as WampServer.
WampServer has some configurations you must pay attention to. If you are ever going to install it, make sure to select mysql on the installation process (since it's more compatible with Joomla) and set mysql as your default ...
Check if the system has free space.
Check in System / Global Configuration / Server Tab / Path to Temp
Folder if you have a full path (not relative one) to the tmp folder
of your website.
Check in System / Global Configuration / System Tab / Path to
LogFolder if you have a full path (not relative one) to the logs
folder of your website.
Check in System / ...
In my case i solve with two lines:
First, I changed the ownership of all files and folders for the user of my hosting.
chown -R groupname:ownername public_html
Then I changed the group's permission to "nobody".
In my case, my server has HWM and the public_html folder needs to have this permission to run the sites.
Change only public_html permission to: