note that our wireless adapters are designed to installed professionally on laptops by the laptop manufacturer, this is why we actually do not recommend, encourage nor support the installation/or upgrade of wireless adapters performed by anyone but the laptop manufacturer. See Intel's position in regards to this at the link below:
I see you also mention that you are using a single antenna, this adapter was designed to use three antennas for correct performance.
I hope I got you on the right track at least.
Thanks for the non-answer. I'll be sure to remember it when considering future purchases of Intel products for my PC builds...
And yes, you did get me on the right track: I am replacing the non-functioning Intel Ultimate-N card with a Qualcomm Atheros card.
And to those who may be experiencing similar connectivity issues I believe the problem is that the Motorola SBG6580 supports 2.4GHz OR 5.0GHz and not both simultaneously whereas the Ultimate-N card uses both simultaneously; therefore I believe them incompatible.
One final update - I installed the Qualcomm Atheros wireless N card minutes ago and it works perfectly. (This post was made via that connection.)