In order to perform its activities successfully, the Internet Information Services (IIS) World Wide Web Publishing Service (W3SVC) must be free of any I/O errors involving file access, memory availability, and network connections. In addition, any scripts that are used must be accessible and running, and any include files must be configured correctly.
Check available memory
For more information about low memory issues in IIS, see the article How to use the IIS Debug Diagnostics tool to troubleshoot a memory leak in an IIS process.
You can also use the link below to get a better understanding of the available memory on the server:
Memory\Available MBytes Performance