This started happening to me after the latest VO update. The fix was adding the following to the top of my config.ini file.

[wavsound]
use_dsound=0

This for my laptop with vista sp1.

Ok i used these settings for vista to make it work all the time:
add the following 4 lines to your config.ini and it should work all the time:
[wavsound]
use_dsound=0
bufsize=8192
numbufs=4

Big Props to Darkbind II! Thank you!

After messing about for quite some time I can across this post and the bufsize and numbufs additions seem to have finally fixed my sound issues under Vista.

I think perhaps raybondo could add this info to his post which has been linked to as the solution in all the other threads I found as simply use_dsound=0 did not fix things for me.

I say this because I was about half a minute from giving up and not looking back when I ran across this post.

But how do you make it let you save the changes!?!

Changes made to the config.ini file not being saved under Vista? I heard about something like this- there's some sort of "feature" in Vista that prevents files installed under the Program Files directory from being modified. Luckily, the solution is easy- just install VO to a directory other than Program Files.

This should also fix the bug where an update is preformed, but VO gets reset to the older version.

[wavsound]
use_dsound=0
bufsize=8192
numbufs=4

Using Vista Ultimate and these settings work perfectly for me after i figured out how to save the changes, you save changes by disabling UAC, google it to find out how.

Yay, Vista sound problem finally solved with update 1.8.36.
VO now uses the native audio system of Vista. All [wavaudio] settings are ignored in Vista if VO is able to use the core audio system. Otherwise it will fall back to wav or dsound. Check out the waverror.log if you want to know which version VO is using. There will be extended information when using native sound.