Long clip import errors on 15 inch MacBook Pro confirmed to be HARDWARE??

Question

Our family has two MacBook Pros, one a 15", one a 13". The 15" is a 2.53 GHz, 4Gb ram, 500G 7200RPM HDD model, the 13 a 2.26, 4 Gb, 250Gb 5400HDD model. All software is completely up to date and we use no third party software other than fusion and MS office on both laptops.
We use the 15" for our iPhoto and iMovie. Our Camera is a Sony HDR CX12.
We have been plagued by the dreaded red import errors trying to import clips from our AVCHD camera. The errors occur when trying to import clips of 2 min or more. We have tried everything imaginable. We dropped the import size to "large" from "full", we tried every setting imaginable, at Genius behest we have wiped the system, reinstalled the OS, zapped and reset every imaginable cache, setting, etc. We've tried aroma therapy and crystals. Tried it plugged in, on battery, tried the USB cable, a card reader, and even camera archives and disk images, quit all programs, all with the same result... error!
In desperation I took the HDD out of the 15" MacBook and dropped it into the 13" (lesser) MacBook.
It just plain works. I can import 12 min clips while surfing the web, downloading podcasts, answering emails, you name it. I put the drive back in the 15" machine and... error. Strangely even short clips the 15" is able to manage import faster on the lesser machine!?
I am guessing iMovie has a hardware ID bug. Usually the MacBook pro has a higher end graphics chip but our 2.53 has the same chip as the smaller MacBooks, might iMovie be expecting a more robust graphics chip in a 15"??
Can others confirm a similar situation.
other than iMovie the 15" works swimmingly.

Answer 1

These ideas won't explain the problem, but might help establish facts and narrow the problem.
On your menu, go to Apple, About This Mac then click the More Info button. This will give you all of the configuration info about your MBP. You can then verify the graphics processor the system has (or thinks it has!).
You could add a new user in Preferences, Accounts. Creating a new user, log in as that user and before and launch iMovie.
I don't know, does Memory Stick have different class levels such as SDHC cards? If so, perhaps trying a bumped up card would overcome some undetectable anomaly particular to the 15" MBP.