Hopefully Google will pick this up and someone else will be spared a couple of days like my last few, bashing their head against a brick wall...
As of present (see date on this entry), most of the F/OSS media players do not appear to be able to play Speex encoded Ogg files correctly. VLC Media Player is not able to do it. Nor Media Player Classic. The Xiph.org codecs don't seem to make Windows Media Player work correctly either. All of the above tend to either not play Ogg Speex files at all, or if they do sort of manage to play the file, they drop the first several seconds of audio.
I have no idea why this is. Perhaps Speex's insistence that there be not one, but two Ogg pages of header data before the page(s) of actual audio data is part of the problem. Or maybe since Speex is primarily a streaming format, nobody bothered to test it on files. Whatever; it's not my job to make F/OSS media players not suck. All I know is that I went to speex.org, download three different .WAV files plus the official speexenc.exe, encoded the files, and none of the above mentioned media players would play the resulting .ogg files correctly - if they played them at all.
The good news is that, after extensive testing of many media players, I found that Foobar2000 does seem to play Speex Ogg files correctly. So if you are unlucky enough to have to deal with this crap (as I am), try http://www.foobar2000.org/ .