Browsers fail.

Internet explorer, opera, firefox and safari all apparently crash and hang randomly while browsing the internet. They go white, and will not close if I attempt to end the process in the task manager. This in turn prevents the computer in question from shutting down correctly; Vista cannot close down the browser(s), and is stuck and cannot shut down/restart the computer. To turn it off, the power button must be held.

Obviously this isn't what i want to do, so i need a little bit of insight as to why this is happening and how I can fix it?

... pl0x

Well, let's start with Firefox:
- How many addons do you have and which ones are they?
- How many themes do you have?
- Have you tried safe mode?

For Opera & Safari:
- Do you have any plugins running?
- What about themes (Opera only)?

For IE:
- Any ActiveX running on the page in the background?
- What about ActiveX addons (toolbars, menu options)?

Finally is there at all a common thread between when they crash? Are they all on the same page, same type of page, or just random?

Have you run a full system virus scan recently?

Have you made any significant changes to your network recently?

Haha, I think what he means is that he's tried all of those browsers, but each exhibits the same problem.

Perhaps you need to try reformatting? Even if your hardware is old, it shouldn't just cause any applications to incongruously stall the OS.