Microsoft has confirmed an issue with Windows Explorer in Windows 8 that causes the component to go into a crash / restart loop.
The problem impacts Windows 8 Developer Preview Build 8102 Milestone 3 (M3), the first public development milestone of Windows 7’s successor.
Microsoft has already identified the source of the crash / restart loop and apparently it’s connected to the Metro tiles, even though Windows Explorer is a component of the traditional Windows 8 desktop.
Fix Windows 8 Explorer Crash / Restart Loop - Softpedia