Please post here if you can't get on and route through level3?

Do a trace route to see if you're hitting level3. Thats where the problems lies I think, is the route through level3s infrastructure. You're ISP might be routing traffic to SE's servers using level 3. Open a command prompt and type 'tracert 199.91.189.24' and see if you see something like this:

Tracing route to 199.91.189.24 over a maximum of 30 hops

1 <1 ms <1 ms 1 ms TARDISNATION [192.168.1.1]
2 11 ms 9 ms 8 ms 10.252.208.1
3 9 ms 9 ms 12 ms dtr02davlvt-tge-0-0-0-0.davl.vt.charter.com [96.34.84.220]
4 20 ms 20 ms 25 ms 96-34-86-208.static.unas.ma.charter.com [96.34.86.208]
5 27 ms 23 ms 26 ms bbr01oxfrma-bue-2.oxfr.ma.charter.com [96.34.2.14]
6 20 ms 20 ms 25 ms ae-57.bar2.Boston1.Level3.net [4.53.56.53]
7 84 ms 69 ms 109 ms ae-10-10.car2.Montreal2.Level3.net [4.69.153.86]
8 32 ms 31 ms 35 ms ORMUCO-COMM.car2.Montreal2.Level3.net [4.59.178.74]
9 * * * Request timed out.
10 32 ms 31 ms 32 ms 192.34.76.2
11 * 34 ms 31 ms 199.91.189.234
12 32 ms 31 ms 32 ms 199.91.189.24