I'd agree with Matthew - these are bottom end specs. What GS state as
minimum requirements and what is required to work efficiently and happily are two different things.
After weeks of testing, I recommended a BIM server with 16 cores and 12 gig of RAM on 64 bit Windows 7. All client machines to have quad core processors with a minimum of 6 gigs RAM, 64 bit Windows 7 (plus 768Mb nvidia cards and dual monitors including at least one widescreen). And that's all just to get started. Everything is readily expandable.
You're also not running the latest hotfix of AC13, but I'd recommend going to AC14. There are many back-end improvements given that TW2 has now had time to mature.
This may not fix the hanging on open issue, but if you're going to be serious about using TW2 the reality is that you'll need to invest in some high end equipment. You'll never look back!
In the meantime download the AC13 cleaners. Not sure where to get them from offhand, but they're very good at cleaning all traces of AC13 when reinstalling. Try a search perhaps?
Cheers,
Link.