Well I just did a quick search for sound alerts and didn't get anything similar.

On MSN7.5 and MsgPlus! 3 I had sound alerts set for certain contacts. So when they signed in, it would make a noise so I would know. Since upgrading to WLM and MsgPlus! Live it sometimes works and sometimes doesn't.

I have checked and double checked the settings, and the contacts are set, and the sounds are set. But when a contact who is selected signs on, it doesn't always make the sound - more often I get no noise than I do.

When they do work they are VERY quiet compared to 7.5 and MsgPlus! 3. I could always hear the sounds above any music or games I had running. Now everything has to be turned right down (Winamp at 30% volume for example, rather than 100%) to hear the sound notification - if it gives me the sound notification.

Any ideas?

I'm guessing the sound you're using is normally a quiet sound anyway, and Plus! 3 was just upping the volume behind the scenes.
I've also noticed that sound collisions are handled differently in Live, as each new toast makes the sound start again.

Your right about the volume level - I played it in a different media player at the sametime as some music and it wasn't audible with the music at 100%, but was clearly audible at 15%.

What about the way that I only actually get the notification sometimes though? Most of the time it doesn't make a noise at all. It's annoying, as there are people I need to talk to, but I don't look at the sign-in boxes all the time (in 7.5 I turned them off because of the people who signed in, then again, and again, and again...). I can't trust the sound alerts to work anymore.

You may want to double-check your settings, though I'm sure you already have.