Poor Decision Making   

On a side note, when instructing for FSI a while ago, the guy training me to be a simulator instructor told me that a far amount of pilots who initially responded to IIMC would, about 10 minutes or so into the recovery, lose control of the aircraft.  Fortunately, most of them would regain control and safely shoot an instrument approach.

I didn't believe him until I started instructing in the simulator.

He was absolutely spot on!  I never keep statistics, but my gut tells me it around 10% to 15%.  And, most did successfully recover and land.  

I started asking the pilots what happened when they lost control, and most (the honest one!) said, "I got too comfortable and too lazy (read - complacent) with my scan.  

A word to the wise, the poster who basically said "practice" whenever you can is absolutely right.  IMC flying in a helicopter is a perishable skill.  Don't do it much, and it's too late to catch up when the real situation arrives!

BTW, a three axis autopilot in helicopters should now be standard equipment!