Error installing plugins: "Could not acquire framework manipulator service"

Using the RCP version of Eclipse Helios on my Windows XP machine, I am trying to install some fairly basic plug-ins like PyDev and EPIC from their standard update sites. Unfortunately, I keep receiving the following error message:

An error occurred while installing the items 
session context was:(profile=epp.package.rcp, 
phase=org.eclipse.equinox.internal.p2.engine.phases.Install, operand=null --> 
{plugin name},
action=org.eclipse.equinox.internal.p2.touchpoint.eclipse.actions.InstallBundleAction).
Could not acquire the framework manipu开发者_如何学Clator service.
Could not acquire the framework manipulator service.

It doesn't look like this error occurs very much as there are very few things online. Everything about my installation of Eclipse is pretty standard. Is there some workaround for fix for this issue?

Looks like this was an extraction issue. One of my plugins didn't get unzipped correctly the first time, causing this behavior. I unzipped it again in a new location and it works fine now.