cant connect to some websites

I can connect to most websites with no problem. However,
there are a few sites I cannot connect to. When I type in
the name (e.g."nashbar.com"(one of the sites I cannot
reach)) the search times out with the standard error
message: "IE was unable to connect to..." The only
difference I have been able to find between sites I can
reach and sites I cannot is found in
File/Properties/Address. The proper address is found here
when it's a site I can reach,
but "res://C:\WINDOWS\System32
\shdoclc.dll/navcancl.htm#http:// (followed by the
address)" appears for sites I cannot connect to. I have
two computers, both running XP, networked through a
Linksys "Etherfast Cable/DSL Firewall Router, Model
BESFX41" to a DSL modem, and both computers behave
identically concerning this problem. Thanks for any help.