Is Quicktime bad for playback, or is there an encode error?

[BadgerKing]

Whenever I play an exported video from Zarx264 in Quicktime, it displays blocky footage. I've tried adjusting certain settings, like increasing the bitrate and trying different deblocking numbers, but it seems like it's hit and miss when I do this. When I play the same video in WMP and VLC, however, there is no issue whatsoever. I also exported directly from Premiere Pro with h.264 and it didn't have any issues either.
I was just curious if anyone else ever experienced this issue, and is it something to do with Zarx264 or just Quicktime in general?

[l33tmeatwad]

Quicktime for windows isn't really the best options for windows users. Having it installed can be of benefit because of plugins and such, but it's probably one of the worst for playback.