Firewire HDD & USB mouse conflict

[babbler]

When doing very 'write heavy' work on a Firewire external drive (Lacie 160Gb) I find that my USB mouse becomes unusable; the pointer leaps all over the screen. The trackpad works normally. With less demand on the firewire, but with the disk still mounted, the mouse behaves normally.

Is this a known issue and is there a fix ?

Thanks

 

[babbler]

When doing very 'write heavy' work on a Firewire external drive (Lacie 160Gb) I find that my USB mouse becomes unusable; the pointer leaps all over the screen. The trackpad works normally. With less demand on the firewire, but with the disk still mounted, the mouse behaves normally.

Is this a known issue and is there a fix ?

Thanks

Oops. The reference to the trackpad will have told you that I posted this in the wrong place. It refers to a new MBP.

BUT. Exactly the same thing happens with my Intel Mac Pro, but it did not become apparent until lots of external drives were working really hard with video processing.