First of all I want to say THANK YOU all the developers of the great software, CCleaner. I use it once a day, it's really helpful.
Well, there is one file with name "WindowsUpdate.log" (It's located on the Windows' folder - C:\Windows\WindowsUpdate.log for example). This file contains a log of the WindowsUpdate function. When it weights alot, the CPU starts to work hardly and sometimes can freeze the computer for some seconds. The fixing of the problem is just to clean the contains of the file, or - to delete it.
I suggest to add a function for CCleaner - to clean this file. It's really can helpful for lots of peoples.