By cache, you probably mean memory. There are tons of freeing-memory freeware programs. Try google.
As for your problem, it's more network related than memory related. Do you get the error message "The connection to the server was reset while the page was loading" with every website, or just specific ones? If it's a specific one, then it's probably that the website is down.
You could try using another web browser instead of Internet Explorer. E.g. Firefox, Opera, ...
update:
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Try doing the following thing:
In firefox, type: "about:config" in the address bar
then, type in "ipv6" in the top filter bar
if the value = "false", right click and select "toggle".
the value now should change from "false" to "true".