Make sure you specify the correct path to the file. If you use only the filename without a path and you save the qvw document in another location then the file you want to load won't be found. The script error dialog will show the complete path+filename where QV expects to find the file.
An example: I created an qvw document that loads an excel file that exists in the same directory. Then I saved the qvw document to another folder. When trying to reload I get the error:
I moved the qvw document to another folder, i.e. D:\QVdata\temp. I used a relative path to the source excel document, i.e. FROM [salestodate.xls]. QV now shows that it expects to find that file in D:\QVdata\temp\salestodate.xls. And it doesn't exist there because I only movedthe qvw document in that location and left the excel file in the original location.