@simhq
How do you connect CF on PC? External (USB) reader or built-in cardbus slot (notebook?) ?
I have external reader, which allows to define CF as harddrive in WinUAE settings.
I guess you have XP, not a Vista/Windows7.
First you must inspect if Windows put a driveletter on that device, when connected. If there is, then use Disk management snap-in from mmc console and remove driveletter. Next on, edit WinUAE shortcut so Target field point to i.e. "C:\Program Files\WinUAE\winuae.exe" -disableharddrivesafetycheck". If you have Vista or Windows7 then you'll have to disable UAC also or make a forced "Administrator" start of WinUAE session. Finally, when adding harddrives in WinUAE, make sure you pot CF disk right on top of other stuff, like i.e. WIndows path acting as virtual Amiga disk.