You are running Windows 8.1. How do I know? Because Windows 8.1 is having its way with your card. As jaycee says, it's fine to let the Resmed reformat the card and re-install the data. The only thing lost is the detailed graph information which has already been copied to your computer. That stuff is only retained on the card for a week anyhow, so after a week the card is repopulated completely.
To avoid the problem, slide the "lock switch" on the sdcard before you put it in the computer, then "unlock" it when you put it back in the Resmed.
Yep. Always lock your card when inserting in computer, no matter what version of Windows you use. But 8.1 is a POS --for many reason in addition to how it handles memory cards.
"Sometimes the magic works . . . and sometimes it doesn't" -- Chief Dan George in the movie Little Big Man
The OP says he is locking the card.
I'm betting it is in the "copy" procedure that somehow is borking something.
Try to not do a "copy" every time. You actually don't need to. If you have the urge to copy the card regularly just to have a backup, then do it every 7 days. But each copy is still losing data unless you give each copy its own folder. ResMed machines are stupid this way. The card hold all data for 7 days. Then day 8, the oldest day has some data dumped to hold the newest day. The data dumped is the details you need to view. This continues until day 30. At that point, ALL data but compliance data (because that's all they care about) is dumped for the oldest day.
Each day, one day loses detail data and one day loses everything. If you have more than 365 days of data, one day is lost completely as only one year is kept on the card. So unless you give each day it's own save folder, it's not doing any good to save the card data itself. As long as the software has it (ResScan or Sleepyhead), then all is well.
But back to your problem. Try to not copy and see if the issue is resolved.
The other option is to remove the card from the machine, wait a few seconds, and put it back in. Repeat about 4 times. If it doesn't accept it by then, just select yes. Every other week or so, I have to do this. Cussin' works, too.
Apnea Board Moderator
Breathe deeply and count to zen.
INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.