Laptop says good connection, but no access

[Guest]

I have wireless networks set up in two houses, both using LinkSys Wireless-G systems.
Everything was working fine in both houses until about a week ago.
Now the laptop connects to the Internet at one, but not the other.
The machine says it is connected and the signal is strong, but I can't get/send email or use the internet.
I've tried the "repair" option and nothing changed. I know the DSL connection is good because the desktop which is also on the network works.
OS is XP.
Any ideas?

 

[End of Line]

Can you ping the desktop/router from the notebook?

 

[cttiger]

desktop does not have a static IP address (per Optimum Online's request) but I can see the drives on the desktop from the laptop.