FSX is a real memory guzzler, and I wonder if your 4MB of system memory (RAM) is sufficient to run the Sim, and any background programs at the same time.
I find that I have to run a "Game Booster", or "End-it-all program", to reduce the number of background programs running, to make more memory available when I run my FSX with insufficient memory available.
My system runs FS 2004 perfectly with my available memory, but generates all sorts of problems, (CDT, reset, OOM, etc,) if I try to run FSX with certain high settings, and without cancelling many background programs!
The rest of the Components, Processor, Graphics, etc, look fine!
..my two-pennyworth...

...!
Paul...FS2004/FSX....Win 7 32 bit, Pentium P4 2.8 GHz, 9500GT 1GB, 2.5GB System RAM.
Win 8.1 64-bit. DX11. Advent Tower. Intel i7-3770 3.9 GHz 8-core. 8 GB System RAM. AMD Radeon HD 7700 1GB RAM. DVD ROM. 2 Terra Byte SATA Hard Drive. Philips 17" LCD Monitor. Saitek Cyborg X Fly-5 Joystick. ...and a Briggs and Stratton Petrol Lawn Mower.