Can't really help you more mate, prolly your router sucks :-/
Maybe a firmware update (or a hard-reset) would help ( i still don't know what router you're using so can't help here either ).
When i say reset i don't mean to unplug it and plug it again, i mean to totally reset the router configuration and build it from scratch.
Also maybe it has something to do with your PC and not with your router? Is your PC the only host on the network? If not, the other hosts have the same problem as you?