Please guys – if you are having a problem you MUST tell us what you are doing, what you are using, in as great detail as possible. Otherwise, there is little we can do.
In Mr r's case, it sounds like he may have a bad MIDIclock source. MIDIclock from a computer is very jittery (at best it has a 5% wobble at 120 BPM, more at higher rates). As a result, it has to be heavily filtered, which certainly reduces responsiveness – stability is usually more important.
In the above case it sounds like the stability is not there, and the resulting frequent tempo changes are causing the glitchy-ness. So, consider either finding a better MIDIclock source, or accepting less responsiveness.