Well, at that point you must have installed something on your computer (either within or outside of FSX) that reduces the amount of memory for FSX and the Airbus within it below a minimum needed amount to display everything correctly.
But again, you are using the product outside of it's specification. There is nothing we can do here for you. Put more RAM into your machine (e.g. 8 GB as recommended), make sure the HIGHMEMFIX is properly added to theFSX.cfg file, and you will not have any such problems anymore.
One solution to having to describe a problem several times is to either type it first in a word processor and then copy and paste it when needed, but an even better way that I've had several customers use is to create a forum post for the issue (which has the added benefit of getting attention from experienced forum moderators who don't have access to ZenDesk tickets. Then if you still need to create a ticket, you can simply provide a link to your post in your support ticket. This way you cover all the bases and will likely speed up having your problem resolved.
NOTE: Moderators don't have access to the back end (Such as customer and purchase information) so we can't help with those issues.
And there you have it, your system is below the specifications for the Airbus.
The problem with the nearly 4GB RAM is, that this is not exclusively for FSX, but it is also used by Windows and all other programs running at the same time. So FSX will get maybe half of it. That's the reason why also the HIGHMEMFIX doesn't have an impact on your system, as it would only kick in if FSX would have a chance to get all 4GB, which it doesn't have.
Furthermore your CPU is below the specification. But that is not the problem here with the outside model of the airbus. That is simply because your system doesn't have enough RAM.