On Windows XP sp3 Midi out (to send midi to modular synth) doesn't work as spected, it sends notes and gates every i.e. 4 seconds.

I can play 10 notes and my synth plays 4 of them and the gate reamins high for i.e. 4 seconds. One day ago with an Edirol FA-101 there was no problem, so as you can see this is a new UFX.

Problem repeats in Ableton Live 8.2.5 (last version) and Cubase 5.5.3

I have conected my Midi controler directly to my synth, passing by the UFX and PC, and it works Ok, so there's no problem with the Synth or the Midi controler.

Driver Version: 3.047
Hardware revision: 3.40

Windows XP sp3
Intel core 2 Quad Q9400
4 GB Ram

Help please