Internet Explorer and Wireless Router

Thanks in advance for your response. I have period
trouble with my Microsoft router and the Internet.

When I access the internet directly thru my cable modem,
everything works fine. However, when I go thru the
router (either thru the wireless connection or wired), I
have period problems. For example, I sometimes cannot
acces sites that I otherwise can access. Also, sometimes
when I use the 'back' button on explorer, it doesn't work
and I get a message that says I can't connect to the web
site. I'd appreciate your thoughts.

THanks