how to overcome 'corrupt and unreadable' message

I am very new to all this and not very technically minded so i am hoping someone can help with very simple instructions!The last 8 ds games i have downloaded seem to have gone onto my pc ok but when i try to transfer to my R4i card i am getting the message 'the file of directory is corrupted and unreadable'. This has not been a problem in the last 2 weeks that i have started to download games for my son so i don't understand why it seems to be happening to virtually every game i am now trying to put on my R4i card. Any help would be appreciated.

 

As i still had all the downloads on my pc i decided to delete that what was on the R4 card, do what you suggested and then transfer them back onto the card from the pc. However, it did not delete everything on the R4 chip for some reason when i asked it to. I put the R4 card into my ds to see what it would register and my ds is now showing a message saying i have a fake R4 card which i know i do not. i have no idea what is going on. i am having a real mare and now don't know what to do!

 

You must have loaded the wrong firmware on your flashcart.
Either go to www.linfoxdomain.com/ds and download the correct firmware, or go to the website listed on your card or card's box and get it.

Rather than just deleting everything, you need to choose Format. There will be no data left on your MicroSD once you format, so backup any games and save files.