8i/f graphics problems

Dear all, I have huge FSX and FS9 installations with numerous add ons. The pc is Dell XPS, Intel Core 2 extreme quad 3 gig,4 gig ram, win 7 64, 460gts gpu.I recently bought the 747 and had no problems. This was swiftly followed by purchase of the 8i/F expansion. I then got skeleton aircraft, malfunctions in other aircraft when accessing menu's or the FMC in the wilco airbus etc and then looked at the forum to find I was not alone. I tried all the suggested fixes to no avail.I have reinstalled FSX over the last few days and the installation and the 747 are stable. There has never been a problem with the MD11. I dare not re-install the 8i/F.1. Would I be wiser not to reinstall the 8i/F expansion until there is a solution?2. As others seem to be running the expansion OK do you think there is anything wrong with my PC specs that if corrected might solve the problem? Best wishes, Peter Chambers