Need some 40D, 17-55 2.8 help

Do I need to change some settings, or am I simply confused?
When set at Av 2.8 , 100 iso, flash on (no + or -), it creates a shutter speed of .6 to 1 sec. Thats when I'm trying to shoot a friend in a moderately lit room, at about 20 ft. It of course blurs unless they hold their breath.
Why will the flash not let it shoot much faster?

Thanks

Canon designed it's cameras to always set the exposure in Tv and Av modes as if there is no flash attached. It acts as "Fill" flash that way.

If you want to set a faster shutter speed, there is a Custom Function to over ride this(see page 155 in the 40D manual), or just use Manual mode on the camera and the flash will Automatically adjust it's own power in ETTL.

Thank you. While hoping for an answer, I realized that if I wanted a faster shutter, I can set the dam thing faster I went to manual, and 125 works fine, even with external flash.
I know something was 'wrong' for that much light does not need .6 sec shutter in a lit room, or probably in dark room.
I have to shoot some groups of kids tomorrow, inside, and was getting worried. Could have used 'auto' but it's a bad word to me.
Thanks for the advice.

Yes in manual you can set it up to 1/250.

This is the best article I have read on Canon's TTL flash system, its philosophy and how it is expected to behave in various modes both on the flash and on your camera:
http://photonotes.org/​articles/eos-flash/

I would skip over the old A-TTL and E-TTL and go right to E-TTL II explanations.

trailguy wrote in post #14250451
I know something was 'wrong' for that much light does not need .6 sec shutter in a lit room, or probably in dark room.

Nope. Something was NOT 'wrong'. The behavior you saw is by design as previously mentioned. In Av or Tv mode, the camera meters off the ambient light, irregardless whether flash is used or not. It's documented in your 40D manual.

trailguy wrote in post #14250451
Thank you. While hoping for an answer, I realized that if I wanted a faster shutter, I can set the dam thing faster I went to manual, and 125 works fine, even with external flash.

yes, it seems manual works best with ETTL flash