As a standalone it has many problems... others confirm it here, as a vst, I use it in qbase, and ableton live on PC with winxp. Re-installing it is silly, why a program would want to be re-installed more than 1 times, to work properly?
This is by design.
It is the pattern edit lock mode.
If you just want to switch patterns use the pattern select keys at the keyboard.
These buttons are for locking (in order to edit) a certain pattern.
It will prevent the pattern sequencer to change patterns when locked.