[Pete R]

you could have had any number of drive line failures. I think running cold may be a little optimistic thinking it will be easy. If all outward appearance seems normal it's internal.. and not an easy fix. Are there any noises that can be heard coming from the clutch or tranny?
My initial guess would be that the pressure plate catastrophically failed. (i had one fail in a Jeep once). There was a "pop" and then it couldn't put enough force on the clutch to move the car, similar to what you described It may also me a clutch disc failure of some type. Given that you tranny feels okay and you didn't mention any horrific noise from it, I would look toward the clutch first.