WordPress Links Do Not Work, Sometimes.

Hi,

I installed WordPress latest version and everything is well, I see my website fine but my friends and Digg.com sometimes doesn’t see it.

For examaple this link:
https://www.tonycai.com/2007/01/13/call-international-worldwide-free/

I see it but some people don’t, can there be anything wrong with the .htaccess? Or anything to do with my host or the ISP’s dns?

Thanks
Tony Cai