SUPPORT

I have a problem with my Maya U5 sound card from the beginning .
Sometimes, when OS starts, my Maya U5 sound card not initializing. No sound, and the speaker’s  icon not coming up. Then I disconnect and reconnect it to the USB-port, it’s working fine.
OS „restart” not helps. After complete „shutdown- and- start” procedure everything looks good.
My other devices,(keyboard, mouse …) connected to other USB controller.
I tried my Maya U5 to connect to the active USB-HUB, but it’s problem not solved.
I am satisfied with my sound card apart from this, because it’s  sounds very nicely, and OSX compatible. I recommended it to a friend of mine because of this.
He bought an other Maya U5 sound card too. He never had problem, like mine, with his card.
We from the aim of testing exchanged the two devices. My computer (same computer, same USB-port) with my friend’s sound card  working wery well since then. But my card on his computer occurs similar problems sometimes.
Firmware: latest release 10 on both sound card.
I think, my Maya U5 is faulty.
Please, help me to solve this problem.

Thanks in advance.