Once the \windows\logs\cbs\cbs.log reaches 2 GB or so, the makecab command that Microsoft uses to periodically archive the file fails. Repeatedly. And every time it fails, it adds its incomplete archive to \windows\temp.
Only resolution I’ve seen is to delete the cbs.log.
I don’t know whether the cause is a particular patch, or whether it’s an accumulation of running many in quick succession that increases the cbs.log size beyond the threshold that makecab can handle, but I’ve been able to reproduce the makecab failure on arbitrary files of sufficient size.
…and I’ve seen this on Windows 7 Enterprise x64 as well as 2008 R2.