I tried Pidgin on my Ubuntu 12.04 and it showed a very buggy behaviour. It could never connect to gtalk and even crashed sometimes in the process. So I decided to switch to Empathy. But it has its own problems. It connects to my gtalk and yahoo accounts, but there is another gtalk account which it can't connect to, and when I try to see what's wrong by going to Edit->Account, the Edit Account window shows for a second and then immediately disappears. I tried re-installing whole empathy package (and reboot a few times in the process), but it didn't work. Any idea what to do now?
Pidgin should be rock solid with GTalk - I've been using it on my Ubuntu 12.04 for about a year now, so I suspect either your system (how did you build/install Pidgin, do you have any unusual plug-ins enabled?), or a networking issue (do you have firewalls or proxies in place that would affect internet access?).
However, Google are also in the process of migrating GTalk accounts to Hangouts, so there might be some issues around that. Some stories report that they're dropping xmpp support entirely, but that would appear to be false - they're dropping xmpp "server" support, so clients will continue to work, but you won't be able to federate your own Jabber servers to Hangouts like you could in the past.