"The file that you selected could not be found. Check the spelling of the file name and verify that the location is correct" when calling ExceService.OpenWorkbook in sharepoint with non adiministrator priveleges

Few days ago ,I have the same probelm with you ,and later I have figured it out,the Solution as follows:

The problem you must configure alternate access mappings which in  System Settings of SharePoint 2010 Central Administration.

you should select you local application,such as Http://sharepoint:22222, and Edit Public URLs ,in the internet box you fill your internet url ,then

click ok,and test, I think you will find it's OK.