File Properties Shows 40.7 Gigabytes Used, Then Shows Zero...

I have a strange problem with this computer running windows vista home premium x64.

If I go to C:\Windows and do a right-click on the "SchCache" folder and select properties,
the size of the folder shows 40.7 GB used.

If I try to open that folder, there is nothing in there. I have "show hidden files and folders" checked
and "hide protected operating system files" unchecked, so it's not a matter of simple hidden files.

Now it gets interesting...if I go back and try right-clicking again on the SchCache folder and select
properties, it no longer shows 40.7 GB used! It says zero bytes!

If I reboot the computer and repeat the whole procedure from the beginning, the folder properties will
return to showing a large number of gigabytes used the first time I select right-click-properties, and
then shows zero afterwards...

Malware and Spyware scans always show nothing. I've run rkill, avast, malwarebytes, tdsskiller, ETC.
and nothing is ever found.

Any ideas what is happening?

According to this page it's related to ADSL

SchCache directory - Profile Management - General - Discussions