Process called "Dock" running at 100% since upgrade to 10.6.8
Found this answer on CNET:


  The problem appears to be an incompatibility with Parallels Desktop 6, which has an option to make Windows applications available in the Dock for convenient access. This incompatibility will likely require an update from Parallels to fix, but until then one option you have is to disable the Dock applications setting for each virtual machine you have configured.