Open System Restore. In the left pane you'll find "System
Restore Settings". Open it and you'll see "Turn Off System
Restore". Check mark the box and and click O.K.,it will
delete all of your restore points. Then go back there
again and uncheck the box. It will reset and start over
clean.
Control Panel / System, select the 'System Restore' tab and turn off
system restore on all drives, it will clear out the old points and give
you the disk space back.