Are you having trouble opening your map in Map Maker, or actually in-game?
If it's in-game, I suggest taking some of the objects out of it to reduce lag. You may also want to turn off water reflction and turn down View Distance by going to Options>>Video, and altering these settings.
Or Hm..Try using "Character Reset" (It is under the 'Chat'' if you log in the golden box)
Or try going to your 'Particle' folder and check if there's anything with an number next to it. (_0 or _1) Good luck.
Or...well, sometimes the particle files (if there are) goes duplicated but with a different number. You should use the search assistant to search for all the recently created particles, and delete all those with the most recent creation time (all with the same creation time but with more or les 2 minutes of diference)
Be careful because if you delete more than you should, it also can cause crashes.
Also i coulkd suggest to have a back-up of your meshes while the game were working, so if you have to reinstall your maps, you just need to restore your meshes and your unexported maps.
Arf it sounds like a map crash - it happens sometimes and it's just to wait until it works again or you could, as mentioned above, just do the "Character Reset" and stay away from that map until it's up again.
Good luck floof.
Cheers// Shallow