Descriptive Problem Summary:
The map editing tool's bad instance editor freezes DM.

Numbered Steps to Reproduce Problem:
Add some DM code for some turfs.
Add these turfs to the map.
Compile.
Remove the DM code.
Compile Again.
Use the map editing tool to remove the bad turfs.
Here's a reference of what it should look like for the problem to occur: http://i47.tinypic.com/ipxk49.png

Expected Results:
Map editor lets me edit that last instance.

Actual Results:
Hard freeze forcing a restart.

Does the problem occur:
Every time? Or how often? Every time.
In other games? Yes.
In other user accounts? Yes.
On other computers? Yes.

When does the problem NOT occur?
Never.

Did the problem NOT occur in any earlier versions? If so, what was the last version that worked? Unsure.

Workarounds: You may add these turfs, objects, areas, or mobs back to the DM code and remove them from the map manually using Find/Replace in the map editor.