Reported files missing during batch conversion of lots of files

[sunny]

I noticed when converting a large amount of JPG and CR2 files using the Batch Conversion/Rename function, some output files are missing even when the batch window says it was converted.

Tried on both version 4.36 and tried 4.23.
OS: Windows XP SP3 (also tested on different computers)

Image Files are within sub-directories and folders.
ie: Folder1 > SubFolder1 > SubSubFolder1
Typical amount of files per folder is roughly around 5000 images.

Average Size of files range between 200K - 6meg

I do notice that under 500 images are normally ok and but still from time to time missing one or two files.

account has administrative permission and there is no restrictions on any files.

Settings for IrfanView is:
Work as: Batch conversion - rename result files
Output format - JPG
Include Subdirectories

Under advanced: I have create subfolders in destination folder

[Bhikkhu Pesala]

Are you overwriting existing files? A common error is to run a batch operation of a folder containing files with the same name, but different extensions, then there are fewer files in the output folder than in the input folder.

Please provide full details of the parameters that you are using for the batch job.

[sunny]

I enabled the "create subfolders in destination folder" under options. During output, Folders are automatically created but after a certain while, I noticed that folders (subdirectory) are created but the folders are empty.

If I select smaller number of files to batch convert, it works fine. This would mean that my parameters are correct. The difference is between selecting under 500 files vs large group of files such as over 10000 files.