why does an ethernet usb adapter work on laptop but not main computer?

Question

Hi i am asking this question on behalf of a friend. He has a combined router and modem which he his trying to connect to his main computer. There is an ethernet cable to connect it to the computer but his computer does not have an ethernet card so he has an ethernet/usb adapter instead. When he plugs it into his main computer the relevant light on the router and the light on the usb adapter DO NOT come on, but if he takes the adapter out of the main computer and plugs it in his laptop both of the lights on the router and the adapter come on..
has anybody any ideas why this may be happening, both he and i are baffled as to why it works in one but not the other. Both are running on XP.
Gratefull for any suggestions. Thank you

Thanks for your input bigrez.
Therouter/modem does have its own power souce ( which is being used ). Neither the main computer or the laptop have the drivers on. Following the instructions that came with the router, all connections have to be mad efirst before anydrivers are asked for. Just can't get the connection to work on the main computer, yet it does on the laptop, we are lsot as to why.

Answer 1

Maybe the main computer doesn't supply enough power through the usb? (usb 1.0 vs. 2.0???)

Is there an external power connection to the modem? If so and you're using it, forget the above. If so and you're not using it, try that.

Are there drivers that need to be installed on the main computer?

Answer 2

Wirelessly think ofyou've got to get a instantaneous router. in case you want a commonplace LAN connection then you quite want to get a bypass-over Ethernet cable and plug it into an more beneficial ethernet port on your computer and set up the computer connection to connect utilising an internet gateway. A bypass-over cable can both be made or offered at an area like maximum ideal purchase. when you're asking this question i'm particular you don't understand the thanks to make a bypass-over cable.