LE 6.0.1 introduces erratic midi behavior

[LSRdigital]

I updated to 6.0.1 yesterday. I tried to install the core audio drivers, but I soon discovered that they are badly crippled and useless, so I promptly uninstalled them, and put the midi driver back in its original place. I decided to start working on a new song today, so I opened up a new session, added a midi track and an aux input, and started penciling in some notes for a drum track. I have an external drum machine that is triggered by the midi notes and its sounds are routed back in through the aux input. After putting together a few bars of the drum pattern, I hit the space bar to play it back, but instead of all the notes I just wrote in being played back, only random bits and pieces actually sent a midi signal out to the drum machine each time I hit play. Since this is how I start laying out every song I record, this is a HUGE problem for me. I reinstalled 6.0, and everything is working as before. Can anyone else see if their 6.0.1 refuese to play all newly placed midi notes?.