Avid says its products do not yet support Apple's latest OS update 10.9 aka Mavericks.
From Avid's support page:
"It is not recommended to use Media Composer, Pro Tools or Sibelius with Mac OS X 10.9 (Mavericks) as they are not supported at this time."
"The uninstaller for Pro Tools 10.3.7 and earlier will not work on Mac OS X 10.9. For this reason Avid does not recommend using Pro Tools 10.3.7 or earlier with Mac OS X 10.9 (Mavericks). PTSW-185438.
Increased -6101 errors with Pro Tools 11.0.2 and earlier using Built-In sound output on Mac OS X 10.9. Pro Tools 11.0.x may encounter AAE error 6101 and Pro Tools 10.3.7 and earlier may encounter DAE error 6101 when using the built in sound output on the Mac with OS X 10.9. This occurs with high frequency at HW Buffer sizes: 32, 64 and 128. It occurs with lower frequency at HW Buffer sizes: 256, 512 and 1024. This occurs with Error Suppression enable and disabled in the Playback Engine. The error message is, "A CPU overload error occurred." PTSW-186179."
Read the full page here.
I'm sure Avid is working on an update to resolve the issues.
Keep you posted.