FS2004 says the memory is not enough.

Hey!
I've been working on FS2004 since long...
Today is the first time, twice already FS2004 says it cannot continue because of insufficient memory.
What could be the origin? Yes, I have installed a couple of new sceneries, and I had one sort of crash when I installed the Dreamfactory LSZH scenery, and uninstalled it again. And after that I got twice, when I was flying, the message that FS2004 had to stop because of insufficient memory.
Where do I have to look for a solution?
Jive1 - Belgium
I've been working on FS2004 since long...
Today is the first time, twice already FS2004 says it cannot continue because of insufficient memory.
What could be the origin? Yes, I have installed a couple of new sceneries, and I had one sort of crash when I installed the Dreamfactory LSZH scenery, and uninstalled it again. And after that I got twice, when I was flying, the message that FS2004 had to stop because of insufficient memory.
Where do I have to look for a solution?
Jive1 - Belgium