excel cannot access the file there are several possible reasons

original link

Microsoft Office Excel cannot access the file ‘c:file.xlsx’. There are several possible reasons:
• The file name or path does not exist.
• The file is being used by another program.
• The workbook you are trying to save has the same name as a currently open workbook.

Solution

As it’s stated here, follow these 2 easy steps. Then you can go back to your normal life!

1. Create directoryC:WindowsSysWOW64configsystemprofileDesktop (for 64 bit Windows) or C:WindowsSystem32configsystemprofileDesktop (for 32 bit Windows)
2. Set full control permissions on Desktop directory above (for example in Win7 > IIS 7 > DefaultAppPool: set permissions for user IIS AppPoolDefaultAppPool)