My suggestion: if there are problems with colour management and you're using a v4 monitor profile, always try v2 and see if that fixes it. Some software doesn't like v4 profiles, which result in mysterious and unpredictable errors. Lightroom didn't like v4 - not sure if that's fixed now. Firefox requires a non-default option to be set.
However, there are few practical benefits of v4. In theory v4 profiles can result in better perceptual rendering - but only (AKAIK) if both profiles are v4 - the profile of the image you're displaying and the profile of the monitor. Generally, image profiles are v2. The ICC rave over them (
http://www.color.org/whyusev4.xalter) but I think the benefits are a bit oversold at the moment.
Andrew Rodney (aka digital dog) knows much more about this, and may perhaps explain this better. But I don't use v4 profiles.