What to do when I get a message that MyReport server launched has access denied for project?

At the launch of MyReport Builder or Viewer TCP / IP, it may be that the service does not have permission to access 
the folder MySystem. On the server where MyReport Server installed in Windows Explorer 
>> select the folder MySystem >> then right click Properties >> Select the Security tab >> then click Add ... 
In the Select Users or Group>> click Advanced and click Search >> Select Network Service >> or if it does not 
>> select Services >> then click OK >> Confirm again by clicking OK 
>> Select NETWORK SERVICE and check Allow Full Control >> Confirm by clicking OK.