3COM Cable modem problem

I just got @home cable internet service. I have it hooked up to a router and 3 computers. The modem
I'm using is a 3com officeconnect with usb. (I'm hooked in with 10BT) For 2 days it worked perfectally.
However today when I tried to use the web it was not working. I thought oh.... no prob and powercycled
my 3com Officeconnect cable modem. The red light flashed as it searched for a signal but the second
the light on the modem turned green indicating the cable service was active, my ethernet link led goes
off! I tried unplugging the cable modem for hours, resetting it and everything.... the second it authenticates
with comcast my link light goes out and I no longer have communication with my modem! I have the modem
hooked to a Ugate router. I have tried new cables and hooking the modem direct to a pc.... as I've said
the link light on my modem stays on until the second the modem authenticates with comcast. What the
heck could be going on?! Thanks in advance!!!  
compuboy1012Asked:
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scraig84Connect With a Mentor Commented:
That is a bit odd - however, not knowing your cable modem specifics, I don't know exactly how it will behave under certain circumstances.  The one thing I will say about authentication is that the problem I have seen most often with cable is having the wrong MAC being presented to the provider.  Most providers verify your identity by the MAC address.  Most cable routers have the ability to spoof a MAC off of one of the PC's in case you have already been using the modem connected directly to a PC.  Is it possible the wrong MAC is being sent to the provider?
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SysExpertCommented:
It sounds like either a hardware problem or a config problem.

Try eliminating the hub and router and connect a computer directly to the cable modem.

Then start adding things in one at a time until you find which hardware stops working.

I hope this helps !
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compuboy1012Author Commented:
I have tried going directally to a pc without the router... no difference.... My link status with the cable modem is fine until I plug the modem into the service.... In other words, if I would plug in the modem and the cat5 cable but not the coax line from comcast the link led stays lit forever! .... however about 3 minutes after I connect the coax line to my modem my link led goes out! The led goes out the second the status led on my modem goes from red to green.
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scraig84Commented:
If it IS a MAC problem, it may be that you are trying the wrong PC for a test - did you try every PC?  Better yet, do you know if your cable provider is MAC specific and that you have the correct MAC configured on your router?
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