I would like to say, before someone else does, that I have checked the Knowledge Base, and came across a similar issue to this.
The issue I'm having, however, isn't it simply stopping at the "Connecting to region" phase of login, but rather the Second Life client - Standard, RC, or otherwise - completely freezing long enough at this point that when it finally does finish logging in. I'm already redmapped and disconnected from the Grid.
I've heard of others having this problem, and it's just an intermittent thing for them. They just try logging in again, and it works fine. However, this happens for me at every login attempt from this computer, and my laptop can still connect fine, so I'm pretty sure it's something in this system itself and I just don't know what. If anyone can help, it would be greatly appreciated.
System Specs:
OS: Windows XP Service Pack 2
RAM: 512MB
CPU Speed: 3.20 GHz
GPU: nVidia GeForce 7600 GS
EDIT: I'll give more spec info if you can tell me what it is you want and where to find it.