Tools/Processes need ArcMap restart before they will run, any ideas?

[Mary_GladnessGroover]

Hi,

I've noticed lately that processes simply do not run and will not provide any messages in the results window (provided screenshot).  When I close desktop ArcMap and re-open, the process shows up in the results window as 'NOT RUN'.  It has been happening frequently.  I've never noticed it before.  Could it be a bug?  Memory issue? etc.  Any ideas?  It has become quite cumbersome.

Thanks in advance!

[DanPatterson_Retired]

never noticed it, but does it only occur for memory intensive tools (like thiessen) or all tools?