Sage Act likes to cause computers to continuously reset and restart. There is a simple, quick fix for the problem by using MsConfig in safe mode to disable the "SQl server VSS writer". Now the computer should stop crashing every time it starts.
Then use the ACT uninstall program downloaded from their web site to uninstall ACT. Then you can try reinstalling it again but I make no promises there! I have seen this problem on a fresh clean install of Windows.