Error when opening an Unity project

I am having problems to open projects on Unity. I am using 5.5.1 version and every time that I start running a project its dos not open. If I try to do this a second time it says: “it looks like another unity instance is running with this project open. Multiple Unity instances cant open the same project” .This problem happens even if I create a New Project and it not solve by deleting the temp file.

2976993--221292--Unity Problem.png

Hello, delete the Temp/UnityLockFile. And run the program, I worked.

I hope and be of your help.