internet explorer not responding

Hello I get the internet exlporer not responding message very often. I use windows vista home premium intel core 2 cpu T5600 1.83 Ghz 4 Mb ram.

This problem has become more and more frequent and now it is to the point that I can almost do no internet surfing. Just today Firefox also started doing the same thing.

I have two separate questions:

1-What is going on and how can I fix it?
2-May be I will want to format my laptop. How can I format my computer? I lost the cd that came with the computer by the way, I think it was for restoring windows vista. If I format, is there a way to restore windows vista again without that cd? (By the way there is a recovery drive D on my laptop, which has about 5gb of data, is that what it is for and I will not need that cd by any chance?)