This is the only place in the source code where the error message shows up:
This error message will display when the `modelprecache` string table has no more room for the new entry. Since you said you clear the model cache on map change it seems like it would be an error in a plugin that gets stuck in some kind of loop and calls the precache function on a lot of unique model path strings. The main thing you are going to want to do to figure out which plugin (or if it's something else like a map) is to identify what these string entries are when they've been added.
The best way to do this is to hook this function:
virtual int PrecacheModel( const char *s, bool preload /*= false*/ )
and log the first argument to a text file. The text file would increment + 1 number each time the plugin is reloaded. This way when the server crashes you can always find the latest entries that lead to the crash and look for anomalies.
I adapted a plugin Franc1sco made to do exactly that. You will need the dhooks with detour support extension:
Logs are stored in your sourcemod\logs\ folder under the `precached_%d.log`.