win7/win8 has a known bug, where the event logs create an endless series of crap files.
If you're on win7/8, head over to c:\windows\temp; check the size of the folder. If it's huge (10GB+) this is probably the fix.
-clear out that folder (delete everything that windows lets you delete inside the folder, leave the folder alone)
-then navigate to c:\windows\logs\cbs
-run services.msc
-stop the windows module installer service
-delete the contents of the c:\windows\logs\cbs folder (don't delete the folder, just empty it)
-start the windows module installer service
problem solved.
Note, I've only seen this problem affect win7 and win8 systems. I don't think it affects win10, so check the size of that "c:\windows\temp" folder first.