Im running a Mac g4 with cubase version 5, a roland jv-1080 and a roland pc-300 midi keyboard plus a midiman midisport 2x2. The problem is when i have got so far into writing a new song (usually after i've recorded some audio?) the midi keyboard stops working and cubase stops recieving sysex but the jv still works unaffected? any advice on this would be much appreciated as its a serious mush burner! Cheers, Olivaffair.

You did'nt say what OS version you are using, or what model G4.

I have a G4/400 and I had better USB performance after I upgraded the firmware, and upgraded to OS9.1.

Check the Apple site for OS and firmware updates.
Also make sure you have the latest drivers from M-Audio.

Also it could be a symptom of a bad Cubase install.

Take a look at the forums at Cubase.net

Oh yea sorry i forgot to say that its a power mac g4 running OS 9.1, and yes it may be a bad installation of cu-base so i shall check it out, i also forgot to say that sometimes during playback of a song all the midi tracks just freeze and stop playing while the audio tracks just carry on so i have to take out the usb lead from the midi-man to the mac and plug it back in and a few seconds later all is back to normal, very strange? anyway thanks for the suggestions, much appreciated. Olivaffair