AF has gone out

Was shooting some landscape/architecture with my XTi and EF-S 10-22, when suddenly the focus confirmation beep stopped sounding and my lens started hunting back and forth in a very narrow range. I tried my 50mm 1.8 mark I and EF 28-135 IS, with the same results. On manual focus I will get the center spot to light and beep when I achieve focus.

Here's the deal. I just got the XTi back a week and a half ago from LifePixel where it was converted to IR and the AF recalibrated. AF has worked perfectly up until today. Is this a minor glitch I should contact LifePixel about, or is it major surgery that only Canon can do? Will Canon even touch it now that the body's been converted to IR?

I am SOOOO upset. We leave Friday on a road trip through the western states, Grand Canyon and all of that, and I had my heart set on getting a bunch of IR landscapes (I can still give it a shot with MF, but, well, you know).

WHEW! Color me relieved. I just discovered the AF had been switched somehow to AI Servo mode. I switched it back now and everything works! I have no idea how it got switched, as I was just shooting normally, but there you have it.

Nothing to see here. Move along.

Yes it happens with a lot of lenses, never stops amazing me how long it takes my brain to wake up and check the darn switch.

Another good one is lenses with focus range limiter switches, if you have MF outside the permitted focus range many don't AF until you MF back in the range or change the limiter.