Oups!
Your script is working fine.
Directory "C:\Rtools\bin" is included in the system PATH and contains a gnu find.exe. Strangely enough, when I manually launch the command prompt with...

Thanks for sharing UUPtoISO.

The batch file UIPtoISO.cmd hangs up before showing the menu on my computer. Looks like a localization issue (FR).

After having switched single quotes into double...