I downloaded some maps from here, but I get a sys dump when they are loading!
 

There are many factors that could cause this. I will list the most common ones.

Did you make sure you downloaded a map for the correct game? If not you will get a sys dump each time you try and load the map (somthing like to many markers followed by sysdump.txt Saved). Make sure the map you downloaded is for the game you are trying to play. Maps will only work for the game they were made for!

Another problem could be an error in the map. Most of the time when downlaoding a map specially from a site like this site that shouldn't be a problem cause we test and review all maps that are submitted here. But they could have got currupt in the upload. Things happen.