Hello,
I wonder if your problem might be because you are changing the TSC0 register one bit at a time - the sequence may be critical. I would suggest to write all bits simultaneously and see if the problem persists. You might also try writing a value that sets the bits MS0B:MS0A:ELS0B:ELS0A to all zeros, prior to writing the combination 0111 that you require for output compare.
Regards,
Mac