I have just loaded a latest (R15102M-071013) build into my player. When I tried to run rombox.ucl (from the file browser) the unit responded with "Cant find file .rockbox/rombox.ucl" (i.e. the file I selected). It also does it when I try to view the version info in the system menu.
When I attempted to extract the latest build to the unit over usb, the extracting software (lZarc)(win2k) did not create a .rockbox directory, even though it shows one in the file view of the archive file.
The hdd is an 80gb I swapped in from my RecV1 which just died. I deleted the .rockbox directory and the firmware file, before unzipping the new player firmware on to the hdd.
edit: Problem solved - one little check box in the extraction software - duh