Our environment permits very restricted access to the internet and, of course, we must use a proxy -- only the host in the pop-up is not it. If it were prompting me for access to the proxy I would have recognized it right away as the hostname is easily identifiable as the proxy. To add to the complication, the proxy only works with IE -- in other words the firewall only permits access to the internet via the proxy AND IE. Eclipse may NOT access the internet, even through the proxy. Makes installing a software and updates a pain.
I do think it's somehow related to version control as the host mentioned in the pop-up used to be our SVN repository. Since you mention opening the EGit perspective causes EGit's proxy plugin to override the default proxy plugin, I wonder if opening the SVN perspective once prompted an analogous action triggering the start of this pop-up? I would not have fiddled with the git preferences since we don't use it. Whether the EGit plugin is installed I don't know (did it come with jboss tools perhaps?). The SVN preferences do not contain a reference to this host, at least I couldn't find one, but it must be related.
I just realized subclipse isn't installed -- doesn't it come with JBDS 7? (that's what I'm upt o now and it's working quite well!)
Thanks for all the info. I'll have to install subclipse at some point and we'll see what happens then...