First of all make sure that the card has no errors. You can check that on the PC using all kind of utilities like Norton Utilities or System mechanic etc or if you don't have those kind of tools use windows error checking (My Computer / Right click on the card / Properties / Go to Tools tab / Use Error Checking.
My recommendation is to never pull out the card without a "safely remove Hardware" on the PC or "Unmount SD Card" from storage on the phone because if a file is written at that moment on the card corruption may occurre in the file system.
Second:
Which file system does the card have, FAT 32, FAT or exFAT? Check on the computer (My Computer / Right Click on the card / Properties
The FAT and even the FAT 32 file system have some limitation regarding the different attributes that the file have. Fore example on the old FAT file system there is a limitation that doesn't let you to write files that have filenames exceeding certain numbers of characters. The FAT 32 improved that standard but still has it's limitations. (Lockup the specification on Wikipedia). exFAT has evolve from FAT 32 with superior attributes(ex. you can writer files bigger than 4 GB) (Useful wen recording video and the file becomes biger than 4 GB), it's a substitute where the NTFS file system can't be use.
In the past i had some problems wile transferring files to the card using a sync application. I had some files that had long file names and because of the Fat 32 limitations the transfer ended with an error....
So if you use the card only in the phone and PC or other device that supports exFAT File System then I recommend formatting the card in the exFAT file System using the PC. For me this change increased the card stability.
If your card is OK then maybe is a software issue and i recommend trying with another card to confirm that. The last resort is a reset but manually backup files belonging to apps that have backup function and stores backup files in the "Internal Memory" . I personally have a few apps that i need to backup their content and those app have Backup function and i only need to copy the backup files to safety and restore them back later..
Anyway I hope all of you having problems find a solution.
Have a nice day.
