big problem exporting music pitch change

Hello all of you this is my first post and i have a big problem i bought the pro 8 and i had paying customers after a day recording and mixing i export the music as an wave and a mp3.
Both are lower and slower and i just dont get it i didnt change anything on bitrate or what so ever!
\What can i do?
The bad news is that i had paying cutomers who just left with a look i dont like and hopefully they are not going to tell other musicians then i can just close my studio.

Anyone with the same problems or anyone with a solution?

please and thank you