Hi
The security starts with the Wireless Router/Access Point.
The Wireless Router has to be set to a certain level and all the clients
have to follow.
If even one of the clients can not follow, the setting of the Wireless
Router's security has to be reduced.
From the weakest to the strongest, Wireless security capacity is.
No Security
MAC______(Band Aid if nothing else is available).
WEP64____(Easy, to "Brake" by knowledgeable people).
WEP128___(A little Harder, but "Hackable" too).
WPA-PSK__(Very Hard to Brake ).
WPA-AES__(Not functionally Breakable)
WPA2____ (Not functionally Breakable).
Note 1: WPA-AES the the current entry level rendition of WPA2.
Note 2: If you use WinXP and did not updated it you would have to download
the WPA2 patch from Microsoft. <http://support.microsoft.com/kb/893357>
The documentation of your Wireless devices (Wireless Router, and Wireless
Computer's Card) should state the type of security that is available with
your Wireless hardware.
All devices MUST be set to the same security level using the same pass
phrase.
Therefore the security must be set according what ever is the best possible
of one of the Wireless devices.
I.e. even if most of your system might be capable to be configured to the
max. with WPA2, but one device is only capable to be configured to max . of
WEP, to whole system must be configured to WEP.
If you need more good security and one device (like a Wireless card that can
do WEP only) is holding better security for the whole Network, replace the
device with a better one.
Setting Wireless Security - <http://www.ezlan.net/Wireless_Security.html>
The Core differences between WEP, WPA, and WPA2 -
<http://www.ezlan.net/wpa_wep.html>
Jack (MVP-Networking).

Below is my OP, here is the solution:

As I suspected I had lost "something", namely the
IEEE 802.1X Protocol. I narrowed in to an application
Aegisl2 which I found in the installation library for the
3COM card.

So I tried this application and was told that the
protocol was installed, did i want to uninstall it?

I did, and then (after a requested reboot) run that same
application again. This time it told me that the protocol
was not installed, did I want to install it? Guess what,
I pressed "Install", and after another reboot my 3COM
card was back in its old good mood.

Thanks to all who came up with hints. Although none
of them solved my problem directly they gave me the
ideas for searching in the right places and for the right
items.

(The reason reinstallation of the 3COM card did not help
was apparently that the IEEE802.1X protocol was only
partly removed and therefore did not install again with
the 3COM card.)

regards Sven