Hardware interference?

Hi. I'm fairly new to this whole topic but recently set up a home wi-fi network. I have a 3com Officeconnect router running in mixed mode. Connecting wirelessly to this I have a 3com 54g PC card in a laptop, a Cameo 54g PCI card in a desktop and a SIS integrated 11b in another laptop. The problem is that I can't seem to have more than one wireless connection happening at once. The first wireless card that connects is stable and works fine but usually any subsequent wireless connections are unstable and I cannot ping anything, get out on the Internet or even log on to the router (I get an IP address however the signal is flaky with BSS timeouts occuring). There is no problem if the other devices are on a LAN cable rather than WLAN. Is this a hardware incompatibility? I understood that the wireless cards are suppose to do a special frequency hopping to prevent interference but this doesn't seem to be working. Any ideas? Thanks.

Is the officeconnect router an AP?

The 3com ADSL router is in infrastructure mode. I can connect fine to the Internet and another PC that is connected if one is wireless and the other is wired but having two wireless connections is not possible most of the time. All devices are set to Infrastructure mode.

It does sound like they're interfering with each other. I haven't seen any evidence of cards of different brands "not playing nice" when connected to the same AP, but this doesn't mean it can't happen.

Do you have a friend who you can borrow another wireless card off? One of the cards may be faulty or just very noisy and thus drowning out the other card?

Failing that, maybe your router is faulty? A lot of the time these things are hit and miss when trying to figure out what is wrong with them. The idea is to take things away from the equation until it stops having that problem. Add things back in until you have that problem again.

I wouldn't think a router would behave any differently to an AP, being that they both should be the same wireless device, only difference is one is hooked back into a router and has more features.

Hmmm I've been looking for that magic checkbox on the router setup page saying "Click Here for Simultaneous Wireless Connections" but alas no.
It would be strange that all 3 wireless cards would be incompatible with each other because it doesn't matter which 2 I have going I get the same BSS Connection Timeouts occuring on the signal status of the 2nd connection that was made. The 1st connection is dominant and works sweet. The problem occurs about 90% of the time. Fortunately I work mostly from my home office and ethernet straight into the router positioned in the office and the wife works wirelessly from the lounge. Found last night that I hadn't enabled NetBIOS over TCP/IP for the WLAN connections (I use static IPs) and once I did this I got simulataneous WLAN connections happening, Yay! But testing again this morning I've got the same problem. Don't know if NetBIOS had anything to do with it - shouldn't have anything to do with BSS timeouts should it?
I'll investigate the router side of things as the clues point that way. Thanks.

Just to update everyone with how I have solved the ?incompatible wireless card problem. After a day of tweaking everything I could think of I eventually tried unchecking the QoS Packet Scheduler on the wlan connections. Hey Presto !!! Two simultaneous wireless connections kicked into life and have been running fine now for over 3 hours even after reboots. All 3 cards are working happily with each other. Thank you (not) Mr Microsoft for another default setting that interferes with hardware and wastes untold hours of precious end-users time.
Anyway I'm glad to have finally cracked this and hope this helps with others who might have a similiar problem.

Cool, glad to hear that you solved the problem and thanks for sharing the solution