Map Manager Error - Fault Code 400 - Invalid URL

I've been chasing this problem for a couple of weeks now, and can't seem to figure it out.

A couple of times a day, users receive the following error:

MapManager
MY LAYER failed to load: Fault code:400
Fault info: Unable to complete operation
Fault details: Invalid URL

When the user reloads the site, all works just fine. There are many services running and called in this SFV (v2.5 with Server 10.0) and the errors are not consistent with just one service. Some days no errors, other days some errors, but a reload of the site always fixes the issue.

Any thoughts on how to eliminate this error or what is causing it.

Thanks
Matt Shetzer