I had/have a similar problem as well, although in my case, like Thomas Detoux's, killing java gave me sound back. I was able to "fix" it by using the ALSA wrapper for OSS applications (package alsa-oss, command is aoss) before launching java. I was losing sound even when the java program I was running did not use sound, although not right away.
I didn't try it with applets, but it make work if you do the same to firefox.
I had/have a similar problem as well, although in my case, like Thomas Detoux's, killing java gave me sound back. I was able to "fix" it by using the ALSA wrapper for OSS applications (package alsa-oss, command is aoss) before launching java. I was losing sound even when the java program I was running did not use sound, although not right away.
I didn't try it with applets, but it make work if you do the same to firefox.