I can copy RAW files taken with the 5D from the flash card to my computer, but I can not delete them. Somehow windows provied the error message that the file is in use by another program. I have no other programs running. Files from the 20D do not have this problem.
Does anyone have any suggestion what is causing this?
Most likely the program used for copying the files isn't finished with them. If you're doing your transfers via a USB cable from the camera, it may be a bug with the Canon WIA driver for the 5D.
I always copy files via a CF card reader, and I can't say that I've run into the issue when moving
files around (Windows imposes the same restrictions on moving files as on deleting in this regard), even with RAW files taken with a 5D.