To flesh that out a bit more!
Go back to your original project and check how it sounds in mono, I'd bet pounds to pennies that FX has something wierd with the phase between L and R channels. Try inverting one of the channels of just this FX might cure the problem.

Don't feel bad, even the big guys get caught. Mate told me of a whole program that went to air with the dialogue reverse phase on one channel, sounded fine in the station as they we're only monitoring in stereo.

Hmmm... "Phase problem." I... have never heard of that... more fool me.
Soooo... how does one account for that? I mean... if it happens to the big boys, what does one do to make sure it never happens again? I tried it on 4 seperate speakers and it worked on all of them. So it seems to only not work on some systems. Correct assumption?
I'd be curious to take a pole: how many systems did it worked for out there - for you guys.
How do I fix this (Farss said "invert the phase" so I can do that)(or, I can change the sfx to mono and put them on the correct side of the screen using Vegas' pan tool).
And, how do I know when it works on all systems? Since it always worked for me in all my tests and systems, I don't know how to make this fool-proof - for a happy fool like me ;-)
Thanks for the help!

What happens is that some computers can't download your sound in stereo. So, both channels are mixed together and if the phase is wrong, frequencies cancel out each other. You may need to check the sound using a mono output (both right and left channels mixed together) to both speakers. Possibly your sound effects were recorded with each channel being out of phase and when mixed together, frequencies get cancelled.
Another possiblity would be that one of the speakers on your Mom's computer, was wired with reverse polarity (neg. to pos. and vice versa). Which would put the speakers out of phase with each other.

In an extreme example when the left and right channels contain exactly the same audio except that audio is 180 deg out of phase when played though a mono system (like most older TVs) you'll hear nothing but silence.

Now take the above extreme example and mix in some just fine stereo music. On a mono TV the music will come through fine but you'll hear nothing of the first sound.

How to check for this problem. There's a little icon in the mixer window, it says "Downmix Output" when you hover over it. That mixes the left and right channels down to mono, use it!
Regularly!
Bob.

Hmmmmm. Thanks, I've never noticed that Icon before. The only Icon I see that I don't know what it means, says 'Dim output'. If that's it, no wonder I didn't know what it was. Dim is not exactly a word I would assume means mix to mono. No Icon that says "Downmix Output".
Of course maybe this is something that's on Vegas 5 and higher. I'll be on version 4 for a while.

You're right, looks like it got added at V5. It's not in V4 that's for sure. It's in V5 and V6 though and I never even noticed it in the release notes but it's a mighty useful addition.
Bob.

waitwaitwait...
I must not be understanding something...
You're suggesting I output in mono, right?
What if I don't wanna?
I mean, no one else has to, right? (I'm sounding this way on purpose, by the way.)
We need our stereo output. And, when I get really good, I'll be mixing to 5.1 - someday. But in the mean time, how do I mix to stereo - safely.
I'm sorry if my questions are very newbie. I'm just trying to understand.

No, NO, NO!

I'm suggesting you should always check how it sounds in mono.
Not everyone has a stereo TV.

What can happen is it sounds just fine in stereo but when it's mixed down to mono (as will happen to anyone with a mono TV) things can go VERY wrong.

How you deal with the problem is another issue, most important first step is getting into the habit of checking to see if you have a problem.

Bob.

For anyone in this game that makes video with audio, PLEASE, PLEASE, buy a copy of Audio Postproduction for Digital Video by Jay Rose, CMP Books ISBN 1-57820-116-0, around USD 44.95.

I cannot stress what a vast wealth of knowledge I've gleaned from that book alone, in fact I'd say a large slice of my income comes from what I've learned from that book. Furthermore Jay is an incredibly helpful guy, on more than one occasion he's given me excellent advice.

No matter if your production is for cinema or broadcast release this book covers how to get it right for your target audience. Why do I rave on about this, simple, it's usually easy enough to see if your video looks like c**p, it's much harder to check if your audio is going to work right in every enviroment that it's going to be heard in.

And here's a tip if you want audio in a TBC that really grabs the viewers attention, look into QSound, only works on stereo TVs and it's probably getting a little overdone of late but used right it still catches me off guard. In brief it lets you create surround sound out of a stereo track.

Bob.