To fix this problem, make sure MetaStock and the download are closed and delete the following file : MS80EXPT.DTA 
it is located in C:\Program Files\Equis\MetaStock 
  
Once you've deleted the file, open MetaStock. 
Then click on tools, expert advisor. 
You will receive an error message saying that the file does not exist and it will ask you if you want to recreate it. 
Click on yes and you should get all your experts back and it should work fine now.