Are you using a router to share the internet connection, or the microsoft internet sharing thingie? (cable modem directly plugged into one of the machines)?

It might be a problem with the cable modem or your cable company, as a last resort. Sometimes this happens on my computer ... despite the send/receive/online lights being on, my router will lose an IP until I restart one of the pcs on the network.

Yes I am using a wireless router-B Linksys, and the cable internet is plugged in the router, the router is plugged in the computer A with a Intel Pro 100m Integrated PCI NICCard, the second mashine B has wireless PCI Card Linksys (Instant wireless series WMP11).
On the mashine A IP is 192.168.1.100 firewall unchecked, on the mashine B --IP is set up "obtaine automatically".

Internet connection like I said, works just fine for some time, then you click on some link and it just sits there without doing anything for about 1-3 minutes, then it would say "page not found..", I close the explorer window or hit "Reload" and the connection is back on, and so on, it's 'on' and 'off'.
Called cable company they said that they don't see any errors on my account, so to them everything is working fine.
Thanks

what make & model of modem r u usin?

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what make & model of modem r u usin?

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modem brand new from the cable company, RCA (digital/broadband)DCM315

Try unchecking "Enable IEEE 802.1x authentication for this network" in the advanced options for the wireless connection.

I just set up a LinkSys Wireless-G 802.11g & b system, and had to work out some kinks myself...

from the above excerpt it seems that you have one sys configured to use a set (static) ip address and the other one is set to obtain the ip address automatically (DHCP). although i don't think this is the cause of your current problem (although it may well be), having your network setup this way can definitely cause connectivity problems. the reason for this, and again going by the excerpt above, if sys A is confiugred with a set ip of 192.168.1.100 and sys B is set to automatically obtain an ip from the linksys router, the router has no way of knowing that sys A has that ip address. as a result, if by chance the router gives sys B that same ip address (192.168.1.100) via DHCP, you're going to have a headache. (fyi, you can check what ip address each sys is using by going into the network props for the nic, clicking on the support tab and then clicking the details button.) i'd recommend that you configure both systems for DHCP (automatically obtain ip, and depneding on your needs, DNS server address as well), and see if by chance your prob clears up. if not, try bypassing the router & connect one of the sys's directly to the cm for an appropriate length of time and let us know if the prob is solved or not.

I have this exact same problem! I used to use Cisco wireless 350 cards in my laptops with no problem. I just got an IBM Thinkpad with built-in Intel wireless and now I get this intermittent problem where my Linksys gateway/switch goes offline every 10 minutes or so! Then it mysteriously comes back. When it goes offline, I cannot ping the inside address (192.168.0.100) which is my default gateway. I can't ping it from my wired desktop either! It's like the entire switch is going in to la-la land for 10 minutes, then comes back. If I use my other laptop with Cisco wireless, no problem. If I use my desktop, no problem. But as soon as I use my new IBM (wireless) it freaks out! If I turn OFF wireless on IBM Thinkpad and use built-in wired LAN port, works fine! What the heck is going on?? Thanks for any help!
-Kevin

This might seem really stupid but I had the same problem with one of my computers (and not the other). The first computer is hooked directly to a cable modem, the second uses a Wireless G USB network adaptor. The Wireless USB adaptor kept "losing the signal" and the internet connection. I had to move the USB adaptor away form my printer (I'm not joking here) and up on a shelf! Hope this helps!

There is a definite incompatibility with Linksys and IBM Thinkpads with built-in Intel Wi-Fi 802.11b cards. I switched to Netgear and have had no problems whatsoever anymore. Threw the Linksys in the garbage!