Why are the files in the hotfolders not recognized?

Problem description:
Hotfolders are not running
Files are not processed
No jobs are generated
Input files in hot folder are not recognized

Solution:  Perform the following steps to get the hotfolders running again
 
1. Clean the job lists:
Fully close ColorProof (including tray icon)
Go to C:\Program Files\GMG\ColorProof05 > double click dbsetup.exe > Service Functions >
Click 'Delete all Jobs':

2. Show hidden files:
Check the hotfolder input folder, whether there are hidden files. These may prevent the file recognition of the hotfolder. Activate the following settings to show the hidden files:
Explorer > View > Options > View > Show Hidden Files, Folders and drives > activate || Hide protected operating system files > deactivate
 

3. Delete all files from the hotfolder input paths

4. Restart ColorProof