When you say your external drive crashes your system,
Do you mean on boot? Or its unplugged, you boot to windows, you plug it in and it crashes your system?
If its the first, boot your system without the drive plugged in, attach the drive and get your stuff, format etc
If its the second, do it again and record the time it crashes, boot ahain without the drive and check your event log for errors relating to the drive and let me know the error codes
Start menu > type event log > check application logs and system logs