IIS - Service Unavailable - Stop pool

I have IIS where run my WebApp and lately every day several time Stop pool and I get Service Unavailable HTTP Error 503. The service is unavailable. Then I have to Start pool and WebApp works. In Server Manager => Events I get this:

Application pool 'url' is being automatically disabled due to a series of failures in the process(es) serving that application pool.

A process serving application pool 'url' terminated unexpectedly. The process id was '6360'. The process exit code was '0xc000041d'.

A process serving application pool 'url' terminated unexpectedly. The process id was '9456'. The process exit code was '0xc000041d'.

A process serving application pool 'url' terminated unexpectedly. The process id was '6156'. The process exit code was '0xff'.

A process serving application pool 'url' terminated unexpectedly. The process id was '4964'. The process exit code was '0xc000041d'.

A process serving application pool 'url' terminated unexpectedly. The process id was '10168'. The process exit code was '0xc000041d'.

A process serving application pool 'url' terminated unexpectedly. The process id was '4812'. The process exit code was '0xff'.

A process serving application pool 'url' terminated unexpectedly. The process id was '3776'. The process exit code was '0xc000041d'.

A process serving application pool 'url' suffered a fatal communication error with the Windows Process Activation Service. The process id was '9764'. The data field contains the error number.

A process serving application pool 'url' terminated unexpectedly. The process id was '7656'. The process exit code was '0xc000041d'.

A process serving application pool 'url' suffered a fatal communication error with the Windows Process Activation Service. The process id was '4704'. The data field contains the error number.

Application pool 'url' is being automatically disabled due to a series of failures in the process(es) serving that application pool.

A process serving application pool 'url' terminated unexpectedly. The process id was '3412'. The process exit code was '0xc000041d'.

A process serving application pool 'url' terminated unexpectedly. The process id was '6332'. The process exit code was '0xff'.

A process serving application pool 'url' suffered a fatal communication error with the Windows Process Activation Service. The process id was '1136'. The data field contains the error number.

A process serving application pool 'url' suffered a fatal communication error with the Windows Process Activation Service. The process id was '8716'. The data field contains the error number.

What should I do. How can I fix this problem? Thx.