Missing Taxi way lines, missing terminals, and black screen

I was wondering if anybody could help me out with a situation I am having in FSX. I have been flying the Level D 767 quite a bit, but this problem I have noticed while also flying the PMDG 744, flight1 Super 80 Pro.After a long flight, one that is a couple hours, when I land at the destination airport, I will find that all taxi and gate markings on the pavement are not there, and in a worst case scenario, the terminal building will not be there. And when I try to bring up a screen like the map, or settings, the game will return with the black screen. There have been times also that menus will not show up with the text labels, only the backdrop so I have to guess at where certain functions are in the menu.Now, I fly with FS2Crew, and LD4, so I wind up spending about 30 minutes at the gate before I ever pushback, I used to fly with FS Passengers, and that is what really made me nervous, because that program switches uses a full screen to display messages and to finish up flights, and almost 100% of the time, FSP will return to FSX with a black screen, which pretty much means game over, since you can never get the graphics back. My set up is FSX w/ Acceleration, installed fresh using NickN's guide, FSX is installed on a Raptor drive with only other add-ons like GEX and REX. Almost all other add-ons are installed on a seperate hard drive, I dont believe I have any add-ons that arent something like a flight planner installed on the same disk as Windows.I have UTX, REX v2, GEX, to enhance FSX, with Radar Contact v4, ASA and usually FS Commander running on a WidePC.My rig is a liquid cooled i7 Extreme 975 (clocked to 4GHz), with 6GB 1600 DDR3 Ram, a 285GTX w/ 1 GB GDDR3. Windows Vista Ultimate 64. I feel like the missing taxi and gate markings, and missing terminals, and the black screen are all memory problems, but I have 6 GB or Ram, I dont get why I should be having memory problems. I read somewhere that UTX's shoreline class creates stupid amounts of unneccesary calls that can create memory problems.I am asking for some help, advice, anything really because I searched around and have not found the missing taxi way lines mentioned. I have seen black screens talked about. And I used to fly with Direct X 10 preview on because that eliminates the black screen about 99.99% of the time, but you get a lot of jagged lines, no airplane lights, and the flickering taxi and runway markings. Any help would be appreciated. Am I running too many add-ons? Is my system not as good as I think it is? Scott Kalin