I just tried both sites on my old Mini with 10.5.8 and both go right in. Reason I was curious is with 10.3 Panther in the last year there are a couple of sites that just sit there and will no longer go in. It's the old version of Safari and the changing WEB of today, but in 10.5's case, that is not the issue. Will see what I can figure out.
Do you know much about the terminal? If so, open it and ping
Yahoo!. See if you get replies from the site. Also in the browser, enter in the IP of Yahoo instead of the Domain name. Can't hurt to try!
Reason for this is trying to see if it's a DNS issue.
Here is the IP for Yahoo. 72.30.38.140
This is what I see when I ping Yahoo in the terminal.
Denniss-iMac:~ dtravis7$ ping
Yahoo!
PING ds-any-fp3-real.wa1.b.yahoo.com (72.30.38.140): 56 data bytes
64 bytes from 72.30.38.140: icmp_seq=0 ttl=56 time=13.410 ms
64 bytes from 72.30.38.140: icmp_seq=1 ttl=56 time=98.707 ms
64 bytes from 72.30.38.140: icmp_seq=2 ttl=56 time=106.712 ms
64 bytes from 72.30.38.140: icmp_seq=3 ttl=56 time=31.367 ms
64 bytes from 72.30.38.140: icmp_seq=4 ttl=56 time=103.171 ms
64 bytes from 72.30.38.140: icmp_seq=5 ttl=56 time=13.823 ms
64 bytes from 72.30.38.140: icmp_seq=6 ttl=56 time=68.178 ms
64 bytes from 72.30.38.140: icmp_seq=7 ttl=56 time=18.497 ms
64 bytes from 72.30.38.140: icmp_seq=8 ttl=56 time=82.927 ms
64 bytes from 72.30.38.140: icmp_seq=9 ttl=56 time=62.739 ms
64 bytes from 72.30.38.140: icmp_seq=10 ttl=56 time=40.681 ms