After installing RC6a, I got problems with my Realtek ALC 260 codec. The codec used to work with Uniaudio, more preciesly, I was able to play WAVs, I wasn't able to play audio CDs. But the WAVs were enough for me.
After installing RC6a, only the operating system can use the sound card. When I try a WAV from an application, I get no sound and I lose the sound completely. The only way (known to me) to get the sound back is a reboot. This happens even if I try to play a WAV from, for example, the Chess game or from the
Solitaire, so that the problem isn't caused by badly written apps.