I have a 2 year old Toshiba Tecra M3 which has been giving me the following problem for about a year, maybe more.

I'll be logged in to the internet using the built in wireless, and suddenly I will lose my connection. The Wireless Network Connection Status window will show me as connected with excellent signal, but my web browser (Firefox or Internet Explorer--happens with both) will give the Unable to Connect message. (Meanwhile my husband will be connected on his Fujitsu LifeBook and be having absolutely no problems.) The only way to re-connect is to re-start my computer. Sometimes a few days go by without this happening, and sometimes, like today, it happens multiple times. I have not been able to pin it down to a particular sequence of keystrokes, whether it had been hibernating, or anything. It appears to be completely random.

Any ideas?

Try to find updated drivers for your wireless from toshiba.com. Look under the Support Section. Also make sure that you aquire ALL windows updates.

You did not say if your husband's connection is wired or wireless.

investigate the wireless router specifications and look to see if it supports
both B and G modes. If so, force it to G mode only in the configuration page.

There's a known problem for dual mode WiFi where neighorhood users are on B mode
and you are on G mode. Your router will attempt to switch modes and thus you
loose the connection.

I loaded the current updates last night. Just had the same problem happen. Thanks for the suggestion, though. It certainly seems like something my husband should have suggested when I began having this problem...

His laptop connection is also wireless.

Oooh, your suggestion is most intriguing. I will look into it. Thanks!