Sometime on startup or shutdown I will get a popping sound through speakers. Sometimes when I am just using Ubuntu I will get a poping sound through speakers. Audio appears to play fine and I never hear any popping sounds while playing audio such as I have searched many threads on this but I can not find a fix for the ATI IXP. Is this a bug or if not can someone help me figure out how to fix the problem?

I am using Ubuntu 11.04 Beta 2 Natty Narwhal 64 bit.

My built in sound:
00:14.5 Multimedia audio controller: ATI Technologies Inc IXP SB400 AC'97 Audio Controller (rev 02)
    Subsystem: Hewlett-Packard Company Device 30a4
    Flags: bus master, 66MHz, slow devsel, latency 64, IRQ 17
    Memory at c0003400 (32-bit, non-prefetchable) [size=256]
    Capabilities: <access denied>
    Kernel driver in use: ATI IXP AC97 controller
    Kernel modules: snd-atiixp