Using nop 3.1
Storing images on the file system, not the database.
I have had intermittent error pages appear when searching for products or trying to open a product page.
The error in EventViewer is: 4011 An unhandled access exception has occurred.
[update] nop log shows: System.UnauthorizedAccessException: Access to the path 'D:\DieselWeb\content\images\0003229_0.jpeg' is denied
Security for this folder is set to Full Control for SYSTEM

The second attempt always succeeds.

Here is what I THINK is going on:
The system tries to create the thumbnail in the correct size.
The system tries to fetch the file before it is created and returns the error.
By the time I try again, the files are created and everything works fine.

Anyone have a fix or explanation?