The hanging at boot is likely just a manifestation of the freezing problem (it freezes during boot basically) -- but if it's repeatable, then it's likely related to the fact you can't boot the w510 with just about anything connected to the USB port.
As for the freezing, I've had multiple system board replacements for this very reason. The first thing support will want you to do is rule out static, RAM and drivers as a problem.
To rule out static - shut down and unplug the laptop. Pull the battery pack. Press the power button 10 times in succession. Put the battery back in and power up.
To rule out RAM - try to beg/borrow/buy/steal RAM if you can, and replace what came with your system. And/or,run memtest. http://www.memtest.org/
To rule out drivers, you need to have the system freeze somewhere other than Windows -- for me, I created a bootable CD of the Memtest (http://www.memtest.org/) and it would frequently freeze there, even when not actually testing the RAM.
Once you rule out those three things (static, RAM, OS), then you can pretty easily get a new system board. If you didn't get the onsite warranty, you might want to go buy one now, BEFORE you open the case, otherwise you'll be without your laptop for some time while it's shipped and repaired.
On the plus side, you may end up with the newer system boards and hopefully those are more reliable than the first generation. 
