Sorry about the missing information. I'm so used to having my system specs posted in my profile, that I often forget to specify when I'm on other forums, unless it has a direct connection to a specific part of the system. Specs are at the bottom.
OOM is short for Out Of Memory.
Prepar3D is actually Microsoft FSX, only further developed by another developer, but it's still using the same game engine, so it kind of hard to believe Microsoft doesnt take into account their own structures.
And it's not that I'm blaming CleanMem, I already posted on other forums, but noone knows CleanMem. So to get help, the CleanMem forums seemed like the logical place to go.

And knowing that some setting in an unexpected corner of the system can make or brake the combination of two parts in a system, I'm not putting blame on anything at all. I'm just hoping to find which setting to change to get this small bug eliminated.
I'm using a pretty standard system, running Windows7 64-bit and from experience I can tell that Prepar3d can use about 3.5GB RAM on top of what the system uses, which is about 1GB. Normally around 4.3/4.4GB total RAM use I get the beeps telling me that RAM is running low and Prepar3D will close with an OOM message. That's what I use CleanMem for, to keep RAM use under 4GB, because 32-bit can use a max of 4GB RAM and above 4GB its getting in the 'danger-zone' of causing OOMs.
Only since I've been using CleanMem, it mostly works fine, reaching 3.8/3.9GB of RAM max, but sometimes it happens that Prepar3D closes with an OOM message, with even less than 3GB used.
Problem with FSX/Prepar3D is that it doesnt always clean up memory that is used for textures that arent in use anymore, and should have been deleted already, driving up RAM use higher than it actually needs to be.
Mostly RAM-cleaners are big problem makers with flight simulators, causing stutters, CTDs(Crash To Desktop) and unstable behavior. But then I read that CleanMem works different from other RAM-cleaners, so I thought to give it a go. And so far, over the whole, it seems to work perfectly.
If I can find where those premature OOMs come from, I think a lot of people are going to be interested in CleanMem.
My system:
Asus Z87-k
Intell i7-4770k @ 4.3GHz
Corsair Vengeance 8GB @ 2133MHz
2x SSD, one for Windows and one for Prepar3D, 1x HDD for other software
Gigabyte GTX780 3GB
XFX 750W PSU
Saitek yoke/rudder/trim wheel/panels
CH throttle
VRInsight T&T
Software:
Windows7 64-bit
Prepar3D 2.4
ORBX FTX Global/Vector/OpenLC/Regions/Airports
Pilot's FSG2010
ASNext
REX4
SPAD
Plan-G