Descriptive Problem Summary:

Certain diagonal pixel movement-enabled collisions seem to cause Daemon/Seeker to lock up.

This seems to be the result of the secondary attempt to fix this bug:

http://www.byond.com/forum/?post=2382531

Specifically this fix is what caused it:

http://www.byond.com/forum/?post=2385557

I've amended the test case I provided for the bug initially to include a second position that fails on 512.1438, and now freezes in 512.1439 so you can get a better overview of what's happening here:

http://files.byondhome.com/Ter13/testworld_src.zip