That usually means "File system full". And that usually happens because you're trying to copy too many files or the wrong files to the [Config] section.
As some of the other replies suggested, delete ALL *.pmm files from the Config folder on your PC, then re-extract them from the zip file. That will leave you with only the files that should be there and not files from previous releases.
P.S. You only need to copy the *.pmm files to FlahScan that you expect to use. You don't have to copy them all.
i.e. if you are only intending to log LS1 98, LS1 99+, E40 and E38, then all you need to copy to FlashScan are the files:
LS1A_A.pmm (LS1 98 auto)
LS1A_M.pmm (LS1 98 manual)
LS1B_A.pmm (LS1 99+ auto)
LS1B_M.pmm (LS1 99+ manual)
E40.pmm (E40 ECM)
T42.pmm (4/5 speed TCM)
E38.pmm (E38 engine)
T43.pmm (6 speed TCM)
You can even delete unwanted entries from Options.ini to make the PID selection menu on FlashScan more compact.
Regards
Paul