I have been using a program (EPX 5.5) for year which allows uploading of photos to a website (eventpix.com) and I have not been able to access the site lately. I get "no reply from server" notices. Eventpix.com support suggests some setting on my firewall or in Avast is preventing access. Recently, I switched to Avast free edition anti-virus and I use Win XP firewall. What settings do I need to adjust to allow access to eventpix.com?

You need to add the program to the exemption list in the firewall and Avast.

You need to add the program to the exemption list in the firewall and Avast.

I believe I did that. Still does not work.

Try downloading a third party fire wall and running that with XPs firewall off. Comodo is a good one. See if you still have a problem, if so it is not the firewall. An easier way is to disable the firewall for a short time but you will be exposed...

I downloaded Comodo, turned off Won firewall and I still cannot connect

that shows you that it is not the firewall at fault. Keep Comodo as your firewall as it is much better that Windows.
Try using another browser, FireFox, Google Chrome, Opera, Etc all free.

I do not use a browser to connect to their website to upload photos, I use their program EPX5.5. I can access the website just not their server to upload. Their support team says it is conflict on my end.

Just guessing here.... some ISPs block or severely throttle ports in certain ranges which are known to be used for file sharing . If your pgm has the option try changing the ports it uses; if not possible then chat to your ISP.
As I said... just guessing. I am totally unfamiliar with your pgm.

I contacted my ISP. They suggested changing my DSN settings, but this didn't work either.