[FX.php List] error 802 when server is stressed?

[Alex Gates]

Has anyone had an error 802 under high server use?
802 - Unable to open file

I have an error checker that will email me when there is an error code 
returned... and I just had one come at me...
It has happened a few times... and today our web app is particularly busy.
Here is a performance chart: 
http://www.gandrpublishing.com/alex/ServerPerformance.jpg

Is this causing an 802?