I am having the same problem and have read in these forums of this browser freeze issue going back to at least March. I have XP Pro SP3 with 3gb ram on a 1.8 GHz dual-core. I flip back and forth between IE7 and Firefox 3.5.4. I don't usually have more than 2 tabs open at once (not much of a multitasker). I'll use a Facebook example (but it is not limited to Facebook usage): I'm transitioning into a Facebook app and it never gets past the "loading ..." message. I click refresh and the screen flashes but the message remains the same. If I click the "x" to stop it from trying to load and then attempt to navigate into another app, I cannot ... but occasionally I can get back to the home page. From there, I cannot navigate anywhere else (even via a link). I close the browser, reopen it and try to connect to Google and get "Found website, Waiting for reply" or something to that effect but cannot connect.
Essentially, I've lost my internet connection (even though other computers in the house have not). The only way to regain functionality is via reboot. Task Manager says ashWebSv.exe is eating 90-100% of my cpu when this happens.
I have literally disabled everything else to determine if there is a conflict and the only time the freeze doesn't happen is if I have shut down avast! before going online, which is really not much help to me, now is it ...
I'm using avast! version 4.8.1201 home edition. I'd hate to have to switch AV programs as, up until about a month or so ago, it suited my needs perfectly and I found it quite reliable. Unfortunately, this freeze up happens multiple times a day and there's no way I want to live with it. Other than the gazillion MS updates that bombard me regularly and Skype (which is almost always off - not just offline, but off), I haven't installed anything new which may have caused the problem.
Any help would be appreciated.