Thanks for the responses. The songs themselves are not the issue because the pitch change only happened when I engaged in the "random" mode which I gathered the software somehow messed up. If I play the same song again either individually or using the "back" button when in "random" mode, it worked fine. So definitely a software glitch but it's weird that different tracks would either play at higher or lower pitch. Maybe I should check to see if the affected songs were encoded at different bit rate thus the varying response.
Pitch changes with digital music???
I was using Plex (beta software) to manage my digital music collection. Recently, when I was playing some music on "Random" mode, I guess the system was running out of juice. In any case, what happened was some tracks suddenly play at higher pitch and the next track lower pitch (i.e., like a record with the wrong rpm). My question, mainly just out of curiosity, is how can it happen with a digital file? Thanks for your input.