Mahjongg-
If you have Windows 10, and the Customizer 10K+ disk - you can upload the software and it will function better than it did on XP. When I had XP, the program did not work correctly so I had to download the 11K version from the Janome website to be able to use the program. It did not recognize any of the ".sew" designs I had that my MC10001 would let me stitch out previously.
When I installed the program onto the laptop with Windows 10... It was just like the program was supposed to run. I could use ".sew" or ".jef" designs and put them onto ATA cards to stitch them out. I've had to purchase a new laptop last week and could not get one locally with Windows 10 on it, so now I've got Windows 11. I'm still learning my way around this new operating system so have not installed Customizer to see what it will do or not do. I'll cross my fingers when I do install the program and hopefully it will still work the same as it originally did and continue like on Windows 10.
Sounds like your card might need to be replaced so you can transfer designs. I'd try a new one and make sure the ATA card is max 512mb memory. Most of the time I purchase 4-8mb cards online from ebay and so there are always new ones that I can use if one wears out.
And while I love my MC10001 machine! I've also purchased a newer TOL model in a different brand due to all the great features the machine offers that Janome does not have at this point, and I won't be able to ever purchase another machine unless I win the lottery.... Someone told me in order to win you have to play! LOLOLOL (I don't play!)
I'm sure your friend likes having you to help her with embroidery!!! Good luck!
Tracy in Nashville, TN
Martha Pullen Licensed Educator