The clock will only come into play on sometimes that are have time logouts which is only a few sites. Is this in Internet Explore, FireFox, Opera or another browser?
Go to Tools > Options > Settings... (under "temporary internet files" section) and select "Automatically" under the "Check for newer versions of stored pages" in IE. Hope that helps!
if this problem will not solve after these given all things. Its mean you are using internet via server which cache setting is out. it will be problem of server then.