I've a strange one.  My FSX will display an OOM while on pause.  I've tried multiple scenery/airplane configurations with the same results.  Unfortunately I don't recall what has changed (a side effect of being old).  Hoping Jim or someone else knows of an approach to fix.  

There are many possibilities for this to occur as things are still happening with the simulator even if the pause button is pushed.  You can setup Process Monitor as I suggest on page 17 of the AVSIM CTD Guide so that only the processes FSX and FSX Add-ons are shown loading.  High autogen, AI, and weather settings will still be loading while FSX is is paused.  If you have photoscenery installed, it will be even worse as large amounts of photoscenery have been known to bring FSX to its knees and crying uncle all by itself.  Photoscenery loads if enabled even if you are on another Continent and thousands of miles from the scenery.  And, if you are changing views while paused to check out the area around you or in and out of the aircraft, your computer will still be loading the images and the textures as you set in the FSX.cfg and Display Driver settings and, if they are high, that will make the OOM occur even faster. 

If you pause near the end of a long flight, the liklihood of an OOM will even increase as VAS usage continues and you are getting close to using all of your virtual address space.

Pausing your sim by going into the settings or scenery library and then back to the flight has been known to provide more FPS and some additional VAS when the flight is continued but it does not eliminate the reduction of the VAS available and the reduction is temporary.  You can test this theory and see for yourself by setting up FSUIPC to monitor your VAS and log VAS usage as shown in the AVSIM CTD Guide, page 16.

It is for these reasons, one would be best served to upgrade to a 64 bit application like P3Dv4 or XP11 or FSW as the VAS is almost unlimited.

Best regards,

Jim