My blade CP Pro does the exact same thing. It will fly for a couple of minutes then it will drop out of the sky 2-3 feet. I have tried different batteries, moved the antenna and it still drops out of the sky. I am going to upgrade to a TREX 450 SE V2 shortly. I enjoy the blade cp pro but they are a money pit. I have upgraded everything to include:
G90 gyro (recommended, do not fly your heli without)
Dual Tail Motors (recommended)
Microheli CNC Main shaft (recommended)
Microheli CNC blade grips (recommended, 3rd upgrade to make)
Microheli CNC flybar system (recommended)
Microheli CNC center hub (not recommended, use the plastic one since the MH one bends very easy)
Titanium tail boom (recommended, 2nd upgrade so you never replace another tail boom)
Super skids (recommended, 1st upgrade)
Park 370 brushless motor (recommended)
Microheli tail support (recommended)
Microheli CNC aluminum frame (not recommended, servo cases do not last long and break at the little holes at top and bottom) cannot use lock tight on
servo cases it will crystalize the case immediately) FRAME looks great, but is to tight and my CP Pro flies better with the 5.00 plastic frame with
Super Skids.

***Do not waste your money on carbon blades for any beginner flight, use the flat bottom plastic type mentioned earlier. The flat bottom blades are stone and stable blades and great for learning. If you are going to use symmetrical or carbon blades use the EFLITE ones. Do not waste your money on the cheap ones, they are junk and will not lift your heli!

***Servos are reversed on the Blade CP Pro Eflite S75 servos. I tried to use some JR servos and they will not work with the standard BCP Pro radio. You must get a new radio if you want to use HITEC, JR servos. You can modify the servos but it requires some work! KISS (keep it simple stupid)

I hope this helps someone out! I have spent some serious cash and have broke just about every part of the blade cp pro. Use the recommendations above to save you money on the BCP PRO.

I am no way affiliated with these sites but highly recommend them due to quick shipping, large selection, cheapest prices, and excellent service:
http://www.eboyztoyz.net/
http://stores.ebay.com/HopMeUp

Do not order from microheli directly, it comes from Vietnam and takes weeks for shipping and you can get it in 2-3 days from the above sites.

Brady