If there is buzzing, then you might wanna consider sending the guitar for setup, adjusting the thrust rod and all.
Straightened out: Your guitar buzzes because the fretboard is bent.. you might not be able to see it cause it's only a slight bend, and that's the reason for the buzzing.
Gathering from what you've told us. May I know if you use a tuner to tune it? Could be due to your tuning. Oh yes, another thing is it a flyod rose bridge? Coz tuning with flyod rose bridged guitars can be tricky, took me quite a while to get it right. If it's a flyod rose do make sure that you place newpapers or a magazine under the bridge while re-stringing. (to make sure it's leveled) Once done, you can take it out. I hope that helps bro