How to debug a browser failing to open web pages? (Safari)

I have an intermittent issue, although persistent enough to be quite annoying, with Safari 5.0 on Leopard 10.5.8.

Go back in time a week...

When going to random web sites, my browsers were failing to load the page. Upon total failure, when I got the "server not responding" error, I hit REFRESH and the page would load immediately.

This was happening on all my household computers, (Macs (Snow Leopard and Leopard and Windows XP IE7) for the last week. I had my ISP come to the house today (ATT U-Verse) and they replaced the router. Since ATT left, my wireless machines are much faster, and all computers but this desktop Mac are error free.

I swapped my two hubs today too, and the problem has stayed with this Mac.

If I use FireFox at the same time, it works perfect and if fast.

How can I diagnose this?

Thanks

I haven't done this on a Mac before, but on Linux I've often managed to diagnose extremely weird problems by using strace. On Leopard, a similar tool is available called DTrace.

The output of these kinds of tools can be voluminous but it might help.

Thanks brewbuck. I found a thread (several) over on the Apple lists, and it seems there are plenty of other folk having the same issues with Safari 5.

After weeding through all the snake oil mentioned in those threads, I ended up adding additional DNS server paths to my settings, and the problem now seems to have gone away.

It seems doing this to any browser is good idea in the big scheme of things.