If you have an RVS4000 and have had a problem with the router blocking websites, this problem has been resolved in the latest firmware upgrade, which you can download here: http://www.cisco.com/cisco/software/release.html?mdfid=282414013&softwareid=282465789&release=1.3.3.5&relind=AVAILABLE&rellifecycle=&reltype=latest.
Although the RVS4000 does provide basic URL blocking, it doesn’t block secure websites (those beginning with “https”) and only blocks exact URL strings (e.g., http://www.google.com but not http://maps.google.com). If you need more robust URL filtering, you may want to consider Cisco ProtectLink Web (http://www.cisco.com/cisco/web/solutions/small_business/products/security/protectlink/index.html).