could not open [file] because of a disk error

[bartonlew]

Hello, I am getting the error message in my subject line when trying to open a very large file (22 GB).  The file is on an external hard drive and all other files on the drive open fine.  In the screenshot below a previous version of the file is opened.  It differs from the one that won't open in that it is slightly smaller (21 GB) and I had started adding adjutment layers to the newer version.  Is the size of the file or the fact that in addition to layers (only 10) there are now adjustment layers added the cause of the problem?  Is there a workaround?  Thank you.  

[bartonlew]

Photoshop says PSB supports documents up to 300,000 pixels in any dimension.  My document is 177,897 px wide.  So that shouldn't be a problem  Still, it is very large at 22 GB.  I am not sure why it is so big as it only has 10 layers and no adjustments layers until I startd adding a few (about 5) in the version that now won't open.  I wodner if I add adjustment layers one at a time and merge them with their associated layer one by one if that will allow me to cotinue working.  Or is there a way to analyze a file to detect the specific problem?  Thank you.