Uhhh, guys? The issue most likely has to due with the game not loading it's drivers/file extension DLL's or another essential correctly on their computer. Deleting duplicate particle files will not help if you crash after the black box window. It's only necessary if you crash while trying to enter a map. They also tried reinstalling multiple times. :/
I don't think you told us what type of computer you use. It might also be helpful to list your specs. (memory, disk space, RAM)