The SSID issue is simple. Buggy drivers on the machine in question. But consider this, disabling SSID broadcast is not a big security gain. I won't discuss at length but you could listen to a recent discussion about it where it was covered. Link -> http://forums.cnet.com/5208-7808_102-0.html?forumID=76&threadID=230041&messageID=2383477
As to the Mac I wonder if you are missing some router firmware update. I just went over such on another make of router and sure enough the router firmware was outdated. If your 3Com doesn't have an update then try another router.
Bob
I have 3 PCs at home that use a 3COM OfficeConnect ADSL modem & wireless router to connect to the internet. I have also a McBook Pro that I just love, however I've a problem connecting to the internet at home. I use a 64bit WEP encryption password and broadcast the SSID and the PCs get connected with no trouble except the Mac!! Not broadcasting the SSID and I get connected but my son's PC doesn't connect!! Why can't I connect to the internet using the WEP password that the 3COM router has set?? Does anyone here run PCs and Mac at the same location and at the same time?? Any help will be greatly appreciated. Thank you.

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