You might want to try the following in order (after every item, reboot and try it out on a few different pages).
1. Upgrade the modem driver. The manufacturer's site should have the latest drivers available. For this, you'll need to know what modem you are using (check the computer packaging list or your computer order).
2. Update the Operating System (Windows of some kind, I take it.) If it is Windows-98, START--WindowsUpdate and let it get all the communication related updates and install them (especially DUN 1.3).
3. Get a utility like TweakDUN
http://www.pattersondesigns.com/tweakdun/ or equivalent and tweak with the packet size settings (first, write down the ones you have as default, so you can go back).
I am sure there will be more ideas posted here in the next day or two. Let us know if it gets better.
[This message has been edited by Narada (edited 17 March 2000).]