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Did you disable System Restore for the External drive?
When you select a group of files and right click and choose properties, it only totals the sizes for files you have access to, which does not include Restore Points or Shadow Copies, When you right click the drive on the other hand, it shows the allocated size of all files by reading the $Bitmap file; it doesn't total up all the files.
With the drive connected, right click Computer, then click Properties.
Click Advanced System Settings
Click the System Protection tab
Wait for the system to stop searching (could take a few minutes)
Is the USB drive checked? If you uncheck it, that should delete the Restore points and Shadow copies. Before unchecking it, I would check the current usage and settings.
You'll also want to check the Max Size settings for SystemRestore/Shadow copies. Some systems have no limit set, so they can get filled with restore points.
To check the current allocation and usage:
Open an Elevated Command Prompt:
Click Start, type cmd in the Search box, press CTRL+SHIFT+Enter
Type vssadmin List ShadowStorage
This will list the limits on each drive, and the current usage.
You also use vssadmin to set the maximum size. (no more friendly slider like in XP)
vssadmin Resize ShadowStorage /For=C: /On=C: /MaxSize=30GB
HTH
Jerry
Did you disable System Restore for the External drive?
When you select a group of files and right click and choose properties, it only totals the sizes for files you have access to, which does not include Restore Points or Shadow Copies, When you right click the drive on the other hand, it shows the allocated size of all files by reading the $Bitmap file; it doesn't total up all the files.
With the drive connected, right click Computer, then click Properties.
Click Advanced System Settings
Click the System Protection tab
Wait for the system to stop searching (could take a few minutes)
Is the USB drive checked? If you uncheck it, that should delete the Restore points and Shadow copies. Before unchecking it, I would check the current usage and settings.
You'll also want to check the Max Size settings for SystemRestore/Shadow copies. Some systems have no limit set, so they can get filled with restore points.
To check the current allocation and usage:
Open an Elevated Command Prompt:
Click Start, type cmd in the Search box, press CTRL+SHIFT+Enter
Type vssadmin List ShadowStorage
This will list the limits on each drive, and the current usage.
You also use vssadmin to set the maximum size. (no more friendly slider like in XP)
vssadmin Resize ShadowStorage /For=C: /On=C: /MaxSize=30GB
HTH
Jerry