Basically sometimes when i load up hotmail or some other sites, they just wont load, i have managed to get a ping response from them in cmd tho. This happens on ie firefox and chrome on any comp connected to the router. Other sites work at the same time. I have had dns problems but changed to google dns so that's resolved. These sites do work sometimes too tho. It's just annoying.
Check your hosts file on you computer. Make sure no entries have been made. Scan for spyware/malware.
As a test, remove the router from your network and see if you still have the problem.
If it goes away, then I would do a factory reset on the router. You'll have to reconfigure it if you had any personal entries. If the problem still persists, try a different router.
If you still have the problem connected directly to the modem and your computer is clean from spyware it could be a problem outside your network which there isn't much you can do.