Internet Explorer "cannot open the internet site "

My Drupal 5.3 (and Drupal 5.2 before that) site recently began giving Internet Explorer users the error message "cannot open the internet site" whenever they visited the site. Through some playing around with modules, I found that disabling the Lightbox V2 module resolved the problem. I also tried jQuery Lightbox with the same results: whenever the module is enabled, Internet Explorer users cannot view the site; whenever the module is disabled, everything seems fine.

Has anyone else experienced this?