PC Light On Cable Modem Box Blinks Off and On & Send Data Light is Not On

Hi Everyone:

       Before I begin, I want to take a brief moment and explain my setup.  First, I have a simply two pc LAN connection.  The first pc in closest to the router is connected to the router via RJ 45 cabling and the router itselt is connected via cabling to the cable modem box.  This pc is working great online and not experiencing any connectivity issues.  However, the wireless pc which has a wireless USB adabpter to receive broadcasted IP information is having problems.  After visually inspecting the cable modem box provided by Comcast, I noticed the PC light blinks on and off in a pulsating fashion and the Send light for Data is not on but the Receive light is on.  All other lights are on.

        Due to the strange network related problems I am having with the wireless pc, I just want to make sure there are not any issues surrounding the Cable Modem box.  Since the first pc connected to the router which is connected to the cable modem box has no internet connectivity issues, I must assume the cable modem box is working fine.  But, I am not entirely sure.

       Any thoughts on this will be appreciated.

       Thank you


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dlonganDirector of ITCommented:
Hi George,

What brand of cable modem do you have?

Normally you will see the PC light blink and send/receive stay solid on.

Okay, in all likelihood, this is a router problem and not a modem problem.  Because your router is that "gap" between you and the modem.  You can intially rule out the modem being a problem because your hardwired computer is having no problems with the net.  If this is the case your modem is functioning properly.  As for the send data light, it is normal for that to be off at most times.  If you were to compare the amount of data you recieve compared the data you send the significance is enormous, if you are browsing the internet and that's all, your ratio could be wide at 9:1 (recieve:send) for every 9 bytes you receive you send 1.  If you are transfering files it's more like 2:1.  So this isn't really a big concern you just aren't sending data out of your modem and to the internet.  Remember if you move files between computers the router is the only hardware that will handle that data, and it won't bother with the modem.  As for the PC light, i'm not sure exactly what that light stands for, but in my research, see if it blinks in a SOS (3 short 3 long 3 short) fashion, that may be signifying that your modem is in fact going bad.  You might check your modem documentation, but i believe it to be a standard function and nothing to worry about.  So then this then appears to be a router problem and not a modem problem, in which the problem will be a configuration issue, and be more difficult to solve without knowing the manufacturer of your router, probably linksys but it could be something else.  Without knowing more about the network setup, the solution to your problem probably won't be found.  Hope this helps...

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i have few question before we solve this issue
-is it possible to ping the other pc from the wireless pc ?
-can you post IPCONFIG result of the two pcs here ?
to do go to Start > RUN > type "cmd" and press enter
in the black screen type "ipconfig/all"
and past the result in here
-and one simple thing to try if you didnt recieve any result from the wireless connection is to change the wireless channel from the router to be channel 11 .
which is not requantly used by other devices , dont forget to remove any wireless phones close to the router.

hope this will help
GMartinAuthor Commented:
Hi Everyone:

        Thanks so much for the quick replies.  I certainly gained much more insights after reviewing each response.  Everything is working fine with the cable modem box.  Apparently, the observations made does not signify any dysfunctioning of the cable modem box at this time.

        On a side note, I found the wireless adapter to work fine.  I tried it out on a friend's pc which was brought over today and it worked greatly.  Therefore, I must conclude there is a problem with software or drivers of the pc which the wireless was originally connected.

        Thanks again for the help.

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