Good Morning All. I am seeking some help from some Commodore experts with a Commodore 1581 floppy Disk drive. Some background: I've been an IT specialist specializing in IBM and compatible PCs since the early 90's. However, I started my computing journey with the TRS-80 model III and Commodore 64. I fell in love with the C64, and it began my start in a very successful career in IT. (see attach photo of my c64 setup in 1986 LOL) Recently I was lucky enough to find a C64C, a C128, and a 1581 3.5 floppy drive online for a reasonable price. Well, I did pay a premium for the 1581, but I never had one back in the day and well, I treated myself.. This past weekend I tested all 3 items and for the most part all worked OK. I was concerned the most about the 1581 working. After a delay in remembering the correct syntax for the C64 format disk command (open 15,8,15,"N0:testdisk,01": close15) - My memory isn't what it was in my younger days! LOL :-D), I was able to format a disk and then save a simple basic prg to it. However, when I try to load this basic prg (on the C64), it locks up the c64 and there seems to be no activity led lights and the 1581. I need to reboot the C64. Now, I tried the same task using the c128 and the same 1581 and floppy disk, I can now format, save, and load a basic prg without any issues. Everything seemed to work fine. My question is, are there any known compatibility issues between the C64C and the 1581 that the c128 fixed? I always thought the 1581 was compatible with the C64 and c64C? Very Strange. Any thoughts and advice are welcome.Thank you in advance. Take Care, Russell LeChard