You probably need to use the ZENworks Agent Cleanup Tool...

https://portal.microfocus.com/s/article/KM000010510?language=en_US

The tool can be found on SLD.  The Current Tool always works with the current or older agent.

The root cause you are seeing is most likely because someone or some tool was clearing files out of "c:\windows\installer".

This is generally not a wise thing.....This is filled with MSI stubs that allow MSIs to be removed w/o the source media.

Hi Craig, thanks for your response! 

I can't find the Zenworks Agent Cleanup Tool. It is still available on SLD portal? Is asigned to one specific type of license? 

Thanks in advance.

Regards.

It "SHOULD" be available for any ZENworks License.  Here is what you want to try and find.

If you cannot find it, you can try opening a ticket.  Even if you are not authorized for an "SR", I presume you could make a non-technical ticket to help get this piece of software that you cannot find but are entitled to.