I know this sounds odd. The JS on my project functions perfectly, except when the web site is accessed using computers at one specific company. To make things even more difficult, the JS fails only about 50% of the time when run from that company. The JS failure occurs with FireFox, Chrome, and IE.

I have tested this myself using FF and Chrome on a thumb drive. The browsers on my thumb always display my project site perfectly, except when run from a computer on said company's network where they fail at the same rate as the installed browsers.

My JS is using jQuery and making some Ajax calls. The Ajax calls are where the failure is occurring. To diagnose the problem I created a logging function for my Ajax calls and recorded success and failure. Over a one month period, there were only a handful of failures (about 1%) from all access points other than this company. Oddly enough, the Ajax calls in the logging function are not failing.

There is nothing exotic there - Just Win XP SP3. I have never noticed any other unusual behavior from their network. The company is a division of a mega ISP and is on their corporate network.

Any other suggestions for troubleshooting would be welcome.