I use it all the time and have had no problems in over a year, which
is only development projects so far, no ACTUAL games as yet. But I
use it a lot with large arrays as Im trying to work out some Entity
swarm logic processes for creating dynamic/reactive asteroid fields.

Dunno about memset problem, but try this one
memset(&(array[25]), 0, 24 * 4);

[EDIT]
This one works for me. Tested with the array defined as
var* array = (var*)malloc((int)sizeof(var)*50);
memset(array[25], 0, 24 * 4);