Hi Antonie,
I have just done some tests under windows and it doesn't have any problems that I can see. I will have a look at Ubuntu eventually but at the moment I don't have a stable build to test with. It may be some kind of timing issue. The USB on Linux is considerably faster than Windows on some things.
Does this problem occur with any test file e.g. an empty file or only with a specific file. I would appreciate if you could re-test with the two example test files please.
Also which specific USBDM hardware are you using?
Thanks
Update
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Tried the attached files with Mint Linux 32 & 64-bit (which is a Ubuntu derivative) and they both programmed multiple times without problems.
bye