Thanks for your quick reply essexboy!

I might have without knowing it. In addition to always having avast! free and malwarebytes, I also use Argente Utilities.
It might have created the autorun.inf folders as part of its one-click maintenance.

It will initially run a scan and show the result as a toaster by the system clock

I didn’t see a toaster. I did see a spinning shield.

Then in the control centre select scanner and tick [b]unhide items on flash drives[/b]

Plug in the drive and McShield will start a scan

Then get the log which will be here :

Start > all programs > MCShield > logs > all scans

And post that

See attachment.

It says it’s all clean. The reason I wanted to delete the autorun.inf folders is that they seem to prevent explorer.exe from displaying drive labels correctly. (“Local Disk” instead of the proper name visible in Computer Management, CMD.EXE and McShield) But if they are necessary to protect from virus, it would be more important than having friendly drive names. I mostly use libraries and shortcuts to access the content of those drives, anyway.