It is WED - not MED!
In WED you have to click Map Properties - there you see Nexus. Increase its value and try to start the game again. Nexus has to do with RAM that the engine reserves for the game.
When you start the game you have the command line, therein the size of the nexus is written too
I'm not using the last version yet, so it could be a bit different.
BTW - try to read the manuals - online and offline - quite often!
From the manual:
nexus
Nexus, i.e. file cache used by the current level, in KB.
Range:
0 .. 200000
Type:
var, read-only
Remarks:
Displayed in the statistics panel.
The nexus limit can be given by the -nx command line option and can be read through the max_nexus variable..
Example:
if (max_nexus - nexus > 30000)
{
ent_create("big_model.mdl",nullvector, null);
}
See also:
-nx, max_nexus, Map Properties, statistics