You can limit the size of the Shadowstorage capacity (this is where the System restore copies are saved). I think it's default size is around 15% of your HDD and for some with small drives or not much room this can be too much. I limit mine to around 6GB as this means I have at least one or two Restore's saved (a system restore size is typically 300MB).
To do this you need to look in your start menu and find 'Command Prompt'.
Then you need to right-click on this and choose 'run as administrator', you will then see a black box open on the desktop. In the black box type this word for word including spaces, it has to be exact otherwise it will not work:
vssadmin Resize ShadowStorage /For=C: /On=C: /Maxsize=6000MB
Then hit enter and if...