This error is usually caused by a corrupted, download and install first an approved Windows Registry Tool to clean corrupted registry.
The easiest way to fix file association errors is to download, unzip and run this EXE file association fix.
CLICK HERE for other Doug Knox file association fix tools.
NOTE: In some cases, EXE file association errors are due to a malware infection on their computer.
CLICK HERE to read more on how to remove malwares.