Where it works for some but not for others, All I can really say is that it is a browser issue. it doesn't seam to be a code issue, if it where, I Would be able to reproduce it. I am not sure what the exact cause may be as I am not able to reproduce it.
you ask about my ISP, I am on Verizon FIOS. But I don't think that has anything to do with it.
To be able to troubleshoot the exact cause, I Would need to be able to reproduce it.