Does anyone ever receive this error when looping through a folder?

I loop through a about a dozen files within a folder on a daily basis. Every so often I'll receive this error showing I am trying to open a file named "thumbs" but there is in fact not file with that name. Anyone experiencing a similar issue? If so, how did you work around it?

It's really not a big deal considering I have error handling in place and it will continue with the next iteration of the loop. Just want to know if this is easily fixable.

Thanks in advance!