Thank you for your reply. I've installed iStumbler and will watch to see what it shows if the dropouts continue.
I have a follow-on question, if you don't mind.
In the iStumbler display, my network shows with a level of only about 70-72%, dropping to below 50% occasionally. May laptop is sitting less than a foot from the Airport Express unit. How can the signal be so weak at such a short distance. As I write this, I see a level of 49% for my network (802.11n) and the next strongest is an 802.11g network from a router across the street at 25%. I'm on channel 1, it's on channel 11. There are some closer routers in my building, but they show less than 20%. Any ideas?
Is there something that might be running on my system causing this? ATM, the only user apps running are Camino, Safari, MS Word, Mail and iStumbler.
TIA.