Occasional headphone out problems with Mbox 3 Pro

[ppiispa]

Hi,

I'm encountering occasional problems with headphone outs on a quite new Mbox 3 Pro. Most of the time both outputs work just fine, but sometimes one of them only puts out static noise. Problem disappears when turning the Mbox off and on again. Problem also seems to randomly affect both headphone outs (but only one at a time), so it seems that headphone amps are ok. Has anyone else encountered similar problems and do you have any idea if this is a hardware or software issue (just wondering if I should return the product and get a new one as long I still can)?

EDIT: Forgot to mention that I'm using the latest drivers, Pro Tools LE 8.0.5 and Macbook Pro 13 (early 2011).

Thanks in advance!