Isto foi respondido nos comentários.
You can try the option
--skipmd5check
. Maybe this helps. See also wiki.ubuntu.com/….
O OP relatou isso funcionou . Mas existem outras alternativas:
[Skipping the integrity check is] not a good idea unless you know the ISO is good (i.e. with a development release).
Remove the CD from F: and let it download a new ISO or the diskimage.
Do you have an apostrophe in your user name? [That] might be causing some issues:
command=C:\Users\TASSO'~1\AppData\Local\Temp\pylBC2.tmp\bin\resize2fs.exe -f C:\ubuntu\disks\root.disk 17744M