For what it is worth. I tested your site as a guest and visited other ubb sites. Some as a guest some as registered.
No Problems.
Using windows xp and firefox and a cable modem from my ISP.
My gut feeling is it is a connection issue from your house.
I know you replaced your modem and I know you changed ISP's.
But your wired connection to the internet is still unchanged.
Meaning you still have the same wires in the house,same wires to the street and the same wires to the telco switching stations. You just pay the bill to someone else.
So that means the only real difference is you may have more or less hops to the internet backbone.
Correct?
So my suggestion is to find out if you have connection troublshooting tools available to you. Call your ISP.
I went through this myself for months with my ISP.
I finally figured out my connection would drop out for anywhere from a few seconds to just under a minute.
My ISP needs at least 60 seconds to log a outage.
And only through constant calls did they finally come out, not to my house but went over all the lines amplifiers hubs and digital converters from a mile away did they finally resolve my issue. It took a very long time.
And they ended up replacing several components including some main lines.
But only after I replaced my cable modem 4 times. That was always the response from my ISP.
But I think it was due to other customers on the same line complaining did they finally send a crew out to check the system.
So I would start with tracert and ping tools which I can only assume a mac has.
Try them both when you do or do not have the problem.
You may find if the first hop fails that it could be the first server you hit. Or something else such as I mentioned.
There really is no easy way to test the wires unless you have some sweep test equipment and then you would need to access the connections at the street and beyond.
