I have had this issue for some time now. I use both Chrome and Firefox on my Macbook, OS X 10.4 I believe. When I am browsing the web the browser randomly stops responding. It appears that it is working and accessing the site but after a few seconds it's apparent that it is not. This happens with or without the two browsers open at the same time. What's interesting is that sometimes creating activity on the other browser fixes the problem. So if Chrome freezes I can click on a website on Safari and that would fix Chrome and vice versa. Sometimes quitting one browser or the other also fixes the issue. Sometimes quitting both browsers and relaunching them also fixes the issue. Also, if I close the Macbook, step away and come back to it sometimes it fixes the issue. Yet there are times that non of this fixes it and I have to reboot the Mac.
None of the solutions above work all the time with the exception of rebooting the Macbook. It's one of those little things that are just annoying and I don't understand what's causing it

. My other computers, which happen to be Windows systems and an iPad don't have this problem.
I use WiFi on the computer and disabling and re-enabling it doesn't fix it. I have not tested this on Ethernet.
Any help from you smart pros would be greatly appreciated.