While there are some new settings on the security page, I don't think that the defaults would stop you from seeing the pages that you mentioned.
Can you give me a specific link that doesn't work?
What is the EXACT message that you get and in what form does it come up (pop up box, web page information...describe the event please)?
Have you changed anything from the defaults at all?
Have you tried to re-install IE 6?
If you don't mind me asking, why are you using IE 6? It's part of the XP core and still in beta. It's really not meant for use by the general public.
JC