I noticed that my ESX server was running on 100% CPU usage today. Upon further investigation I found that “makecab.exe” was using 100% CPU on two VMs. Makecab is the compressor used by Microsoft to compress files. In my case it was compressing Windows Update log files stored in C:\Windows\Log\CBS. One log file was 3GB in size and according to some posts ([1] [2] [3]) the issue is that Windows “makecab.exe” is not able to handle files bigger than 2GB in size. Unfortunatelly it is run from time to time only, so it may happen that it may start up when your file is too big already and you end up having a file larger than 2GB. makecab.exe will then keep running in a loop, trying to compress it, failing, re-trying until you delete the large logfile. It seems save to delete the whole folder content as it is used for troubleshooting only.
In addition, deleting the folder content saved me 20GB of space!