YAPI may see this error on startup.
Most likely there is application that opens too many ports (>5000). This is abnormal. Find this application and kill/restart it.
To find an application use netstat command
netstat -ano > c:\any-file-name.txt
open the file listed above, find the process that has many (thousands) of port opened and find its PID. Using Task Manager, find the process name. Kill the process if you fill comfortable to do so or consult customer IT department.