Bad Request (Request header too long)

This is a bit odd, but every once in a while a user running a Lectora title will get a (HTTP 400) "Bad Request (Request header too long)" error. It happens with different users in different titles on a couple of different servers. But it only seems to happen with Lectora titles.

We publish to HTML. When I looked at the HTTP error log, it is GETs of images, usually several in a row.

Has anyone else seen this?

It there anything that Lectora could do that would cause a request header to be too long? (Like a too large cookie?)

Sign me confused,

Dan