Okay, so ASIO4ALL seemed to work...for about a minute and now the problem is exactly as before. I'm stumped. I'm going to repost this as a question specifically for anyone using the Omega with Reaper. Of course, I'll keep checking this thread, so please feel free to post any other suggestions. Many thanks.

- Can you check the interface on a different computer and with a different host? If you google 'lexicon omega disconnects", you'll find quite some similar reports (for whatever reason) about the Omega (but no solution). - Are you using the interface power supply or is it "bus-powered" via USB?

FIXED IT! So, here's a good tip: don't run your interface through a USB hub, even a powered one. Be damn sure you're running it straight into the computer. Running it through a hub will cause it to drop in and out for no reason and you will spend days trying solution after solution and wasting the time of very helpful people on the Reaper forum. Also, in response to the quote about poor performance from Lexicon's Omega, I have had the opposite experience: good sound, stable performance, good support. I should mention that when I bought the interface, it came bundled with a multi-track program called ProTracks. I think some high school kid must have coded it in his basement--just terrible. But with Cubase, and now REAPER, all is well. Thanks again for all the help.

Glad you fixed it and posted the fix :)

D'OH!! I wish you had mentioned the hub earlier... :D Hubs are okay for some things but a serious no-no for others. Audio/MIDI/Video devices in particular do not get along well with hubs. Oh well... very happy you got it sorted out. ;) D