i believe the error arose after the latest update of the aptana studio eclipse plugin. i tried to remove the plugin from manager configuration pane, but that gives another error: "request operation cannot be performed becuase it would invalidate the current configuration." the details show that there are other parts of aptana plugin that depend on the first, but those components are also dependent on each other, and trying to remove any one of them results in the same error. the main error above only shows on html pages.
thanks for the help!