Radiosity, i know it doesnt exactly fix the problem, but alot of people are using this technique (including myself)

go to the final boss (MINAC) and hide behind the bus, against the rock while crouching, the boss will keep destroying the claptraps it sends out making them drop the required items (eventually) the times however vary, i left mine running for 8 hours today while out and got half of the items i needed, my friend did it for 12 hours and got all the items he needed. i know its a boring way but if your ever going out for the day and really want your 100%

Hope this helps