Have you actually examined the inside of the plastic vent? They will clog with lint over time. Also, some birds like to get in and nest. Can you actually take it loose and see end to end?
Other possibility is that the vent was attached to the dryer incorrectly, so that there is a problem where is is connected.
If there's a free flow of air, then the problem is something else entirely. It could be a coincidence that something else went wrong at the same time the vent was hooked up.

[This message has been edited by rpxlpx (edited March 25, 2002).]

Yes, I can see inside the plastic vent and there are no clogs. It is brand new. It hasn't been hooked up long enough for birds to nest, although I have checked this as well. I'm wondering if it was hooked up wrong, although I'm not sure how this is possible. I know it's a problem with the vent, because dryer works, hooked up vent and doesn't dry, unhook vent and it dries, etc., etc. (tried many times). Is there a trick to securing the vent host to the back of the dryer? Maybe it wasn't sealed tight enough...

Very strange. If you go outside, can you verify that there's a strong surge of air coming out the other end of the vent when the dryer is running?
My only thought is that when it's hooked up, there's something about the hookup that's preventing the air from exiting the dryer.
When the vent is unhooked can you detect air coming in from ouside? Maybe you have a backdraft. Seems like it would have to be VERY powerful though.

Thanks rpxlpx, i'll have to check that out. Hadn't thought of checking outside when vent hooked up/dryer running. Also hadn't thought of a backdraft. I agree - it's awfully strange. That's why I posted, was hoping for some creative ideas as to what the problem could be. I'll let you know what happens.

Is it possible there is a kink in the vent when the dryer is pushed back into place that you can’t see? Using the plastic vent this is easy to do and it will un-kink when you pull the dryer back out to check it.

GlennG, checked that, no kink! It is an awfully strange thing that's happening. Maybe it's my ghost, for some reason she doesn't want me venting my dryer.....

A couple things to check. You said that you can unhook the vent, and the dryer works again. Try
(1) checking the outdoors for warm air blowing out. On most dryer vents there is a flap on the outside shroud (SOMETIMES HELD IN PLACE WITH A MAGNET) and this might be stuck.
(2) leaving the dryer pushed out in the middle of the room with the vent hooked up. THis will eliminate the possibility of kinks in the vent line.

If you attach the vent improperly, the vent will go partially in to your home, which would mean it would work just as well as it always has.

BTW, the plastic vents are really no good. They tend to dry out and crack, and are not allowed in some locales. This can be a hazard with a gas dryer (which I really hope you don't have, since you have not had the vent hooked up).The aluminum ones are better.

Thanks Gump, I'll try those two things this weekend. I'm hoping it's just the flap is stuck, not sure why I haven't thought of that. I don't see any kinks, so don't think that's it, but will check anyway. And no, I don't have a gas dryer, it's electric. I know the plastic vents are cheap, but since it's visible I figured if it goes bad in a few years I'll replace it. I usually check them frequently anyways for damage, blockage etc, I'm a little paranoid about fires, I've heard some horror stories. I'll let you know this weekend how I make out.