Originally Posted by p@rity
Interesting observation... The card seems to throw off my floppy emulator. It started beeping like crazy as soon as I boot up with the card in place. After selecting a boot option it displays the start screen but it won't read the boot-disk image from the floppy emulator memory card. When I took it back out, things worked again.
HxC Floppy Emulator SLIM (build in)
A500 with a non-booting SD Floppy Emulator REV C (external) works well when you select images using the emulator instead of the boot menu.
Your text doesn't mention ACA500 anywhere. Also, the ACA500 does not do anything on floppy signals (no physical connection), and it can't even detect if it's a real floppy or a floppy emulator. You need to find the fault in a different place, maybe your power supply?