Weird sound problem

Hi, I have a very annoying problem.

Sometimes I have no sound when I get a new instant message.
It doesn`t matter if the first message has one or more lines, it`s no
sound; After I reply to it, all is back to normal and the sound works,
always. I tried reinstalling, reinstalling using Revo program, even
reinstalling only messenger without the rest of windows live components;
also tried the repair option; After every install it`s always working
when i`m testing it, after a few minutes again I have the same problem,
with no system reboot or anything.

And this is only happening now and then. Sometimes it`s working ok,
sometimes it doesn`t. And I`ve noticed that it`s happening more often if
that first message is a link; and of course I also get the warning from
the messanger that opening a link, bla,bla,bla. May be that warning
who`s causing this problem?


Thanks in advance.


--
mucifer