connection error on file upload

Greetings. I'm having a problem with my upload handler. If I send small files (under 1M or so), it works fine. if I send larger files, I get the following error in Firefox: The connection was reset. The connection to the server was reset while the page was loading. When using Internet Explorer, the error is simply The Page cannot be displayed. The page you are looking for is currently unavailable. The Web site might be experiencing technical difficulties, or you may need to adjust your browser settings Do I have a problem with my php.ini settings? I've tried a few adjustments but can't find the magic solution. I've just rebuilt the box from scratch, and I must be overlooking something -- nothing I've tried so far works. Any ideas? Thanks in advance. Kenn