Yes, AVAYA is having issues with the G350 Suffix: D HW Vintage: 1, and the new HD MM314 Suffix: C HW Vintage: 1 or 2
They have a "test" release of G350 firmware (g350_sw_27_27_10.bin), but, I have found that replacing the G350 (returning it to your AVAYA ditributor and getting another one) is the fastest way to solve the problem.
In my case, I had 3 different G350's for 3 different clients I replaced all 3 of the G350's, and after upgrading them to g350_sw_27_27_0.bin, they all worked... of course the G350 version now claims to be: Suffix: B HW Vintage: 3, even though before the 27_27_0 firmware it showed up as Suffix: D HW Vintage: 1
AVAYA thinks some G350's where made with 50Mhz oscillattors instead of 33Mhz oscillators.
In any case, your going to have to open a case, and get the G350 replaced, most likely.
mitch
AVAYA Certified Specialist