ASP.Net Hosted Website Access Problems

This happens intermittently all the time, but at times like today, it just go on.
This is what happens:
Our website is hosted by a company in Honk Kong.
No one inside our office, on either of the 2 dsl connections can open our own website on the host, but can surf the internet without problems.
At the same time anyone outside our office (same city, outside china) can open the site.
If I try access the site via proxy like anonymouse.org, I can open it without problems also.

I changed my connection settings any possible way I can imagine without success.

Needless to say the ISP (CNC) and the host just pull up their shoulders