Crucial admitted this issue here:
I saw this manifest itself in the form of an unstable Fedora system running on a 128GB version of the M4. When rebooted the system would appear stable until an hour passed at which point it steadily degraded. There were files that were coming up not found and command execution was giving an "input output error", which is usually indicative of the system not finding the command.
Using smartd we noticed that the "Power_On_Hours" RAW_VALUE was around 8000. The command we used was:
smartctl -a /dev/sda
Just a side note but some other notable info in this output to indicate a possible drive failure are the "Reallocated_Sector_Ct" and the "Seek_Error_Rate".
The fix in this case was to upgrade the firmware. We did this and the system returned to a stable state. Crucial provides an ISO image you can boot to to perform the upgrade, this is a much better option if you are using it as your boot drive.