I love FireFox, as it comes with plenty of good things.
Chrome is quicker, but less secure.
IE sucks sorry but only version 9 does kind of a good job.

For IE 8 go to tools/internet options and on general tab find delete temporary files.
Remove all crap that sits on your PC.
than go to advances (last tab) and find restore IE settings. This will revert your browser to standard settings and all should be fine.
I assume that you had a chat with your ISP and they claim it is your PC ?!?!?!?

Hope this helps.

I can post usfull batch file to clear all temporary files from you PC/laptop and recommend very good defrag tool that actually does the job.

Let me know what is or is not working