OMG!
This is exactly the same problem I have!
It happend once when I download the beta SP1 for vista, so I reformatted the computer cause I thought the SP I downloaded was corrupted, but it happend again yesterday after I ran Windows Update!
32bit programs can't access the internet althought 64bit ones can access the internet (like IE 64 which I'm using right now).
I checked the firewall thing but it's not the issue.
Also, some 32bit programs keep crashing when I try to run them.
I think it's a problem with the 32bit emulator but I have no idea how to fix it. nor does Google since this is the only relevant link I've found regarding the issue.
HELP?