Changing a file extension like that, never really is the best of idea even though it can work in certain cases, I really do not recommend it as it may cause some unexpected behavior from program using those files.
I suggest you use WinRAR. Works wtih A LOT of compression type, pretty all of those you are suspected to encounter. It's free, takes 2 min to install, and it works very well. I'Ve always been using this to compress, decompress files.