FSX ONLY LIKES CERTAIN A/C's

When I use certain A/C's, Overland updated, Eaglesoft Citation X 750 1.0, after long flight when I go to 2D to get airport ILS info or other 2D menu and come back to flying panel, the graphics are all distorted and will not straighten out. If I do a "alr + enter" switch, the graphics will not return to normal. I suspect this is a memory problem. I have changed MB, CPU, graphics card. memory. monitor & OS's and problem has always existed. I have all sliders just abofut maxed except for "mesh, texture set at 10m, 7cm respectively and water effect low 2.x". I don't use DX10 and now using latest nvidia drivers without nhancer. Get very good display and FSP. I thought switching from intel QX6700 (quad) to E8500 (dual) would solve problem but it did not.What is it that makes FSX not like FS9 aircraft for me since so many others have no problem.WilbertASUS P5Q SE PLUS/Thermaltake W0106 700W PSUIntel E8500 - 3.10 OC TO 3.80Vista Ultimate 64 SP2/CORSAIR XMS2 DHX 4GB (2 x 2GB)2x150GB SATA WD Raptor- No Raid/2x320GB SATA WD SE16- No Raid2x IDE Light-On DVDRW 165H65/BFG GTX2603x SILENX 120X25MM FANS + 2x 10in XCLIO Wind Tunnel Case FansDanger Den Water Cooling/Enermax temp/fan controllerFSX ACC@ 1600/1200 |UTX/ASX/FEX/MTX/ASA/REX/UT2/FsPsgrsX/DBS W & F/PMDG 747/3D shockwave/USA & World Extreme Landscape