Server does not show correct amount of storage used

My customer has a Windows SBS 2008 Server. When i take the properties of the C:\ drive it shows 375GB used.  However, when i select all folders within the C:\ drive and take the propertied of them, it only shows 275GB used. How can there be a difference?
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One it might related to hidden/system files not being counted. One it might deal with the page file. Properties oqf computer, advanced system settings, advanced, performance settings, advanced. See whether the paging file is fixed or managed by windows. And it's size.
There are dirstat.
Also space taken by VSS snapshots will not be counted by ordinary folder accounting.
David AtkinTechnical DirectorCommented:
We tend to use TreeSize free to look at file and folder sizes.  Link below.

As Arnold suggests, your hidden and system files probably aren't being counted.  Jmcg is also correct about the VSS Snapshots.

If you're looking to free up some space on the server then have a read through this article for information on how to do so with SBS 2008.

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David Johnson, CD, MVPOwnerCommented:
Explorer will only show you what it has access to.. and normally   hidden and system files are hidden from this display.
Seth SimmonsSr. Systems AdministratorCommented:
agree with jmcg - a lot of that could account for vss

from an elevated command prompt, do vssadmin list shadowstorage and see if that comes close to the missing 100gb
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Windows Server 2008

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