What brand and size of compact flash cards are you using?
On chihiro, it expects a 512MB compact flash card. You can use a smaller one up to 128MB, but you need to partition it like a 512M one.
A bigger CF works as well, but again, I needed it to appear as a 512M
Error 25 cannot access GDROM-DRIVE is what I get when it can't access the compact flash card. I assume if the firmware isn't CF compatible, you might get that error as well as it will only try to access a gdrom drive and not a compact flash. If it has worked before your firmware should be fine.