activity timeout occurs when the timeout of the IIS process times out before the child/orphan process times out.
In the case of PHP the php-cgi.exe is still running but the IIS process times out first.
Error: The FastCGI process exceeded configured activity timeout
if you adjusted the php.ini settings and you still get this error
Open IIS
Top Level server settings
Click FastCGI settings
Select the correct version of the cg exe
change the time out here