This has been seen with the Waves 4.0 Rvox plug-in, possibly others.
Go to waves.com and hit "Downloads". Under the "Quick links" section hit "Updates" and download "Wave-Shell DAE 4.0.1 x".
2. Go to: HD>Library>Application support>Digidesign>Plug-ins – trash the current Wave-Shell 4.0_x and replace it with the new one (Wave-Shell DAE 4.0.1 x).
WaveShell-DAE 4.0.1_X fixes problems, such as loud noise bursts, occurring when issuing Play/Stop commands. If you are using Pro-Tools TDM/LE 6.0 or higher, it is highly recommended to use this WaveShell.
Installation: Go to Digidedign’s Plug-Ins folder (Your Hard Disk / Library/ Application Support/Digidesign/Plug-Ins), trash WaveShell DAE 4.0_X and replace it with WaveShell-DAE 4.0.1_X.