But whenever I do so the program freezes and I have to close it. I have also tryed to use the OBJTOMDL program to convert it and I get an error saying to many vertices or something like that. How do I reduce the number of vertices/polygons so that I can import it? Thanks.

Importing models from other formats isn't in my realm of knowledge as I don't do it. The maximum number of vertices you can have is 65,535. The maximum number of faces is just short of 4.3 billion (theoretically). You need to keep your vertex count less than 65,535.

Download blender.... Blender3d.org i beleive is the site.

Import it into blender and export it to mdl with ventilators export python.
You can get it from the recent contest entries i beleive in the aum section of the forum.

As far as removing vertices you could try to use blenders built in decimator tho most the time it will really mess your mesh up. The best way would be to manually go in and remove edge loops and vertices from unnessecary areas ect.