In Windows XP there was the advanced file type options which could be changed to open each Excel file in a new instance of Excel. In Windows 7 that advanced option is not available. So, when mulple Excel spreadsheets are opened in Office 2007/2010 on a Windows 7 system, all will open in the same instance. A solution is available, but it involves making lile changes in the registry. I recommend making back up for just in case.  Then follow these steps: [more]

  1. start -> run -> regedit
  2. Go to  HKEY_CLASSES_ ROOT/ Excel.Sheet.8/ shell/Open/command
  3. Double Click on (Default) and write "C:\Program Files\Microso Office\Office12 \EXCEL.EXE" /e "% 1" for Office 2007 or "C:\Program Files\Microso Office\Office14 \EXCEL.EXE" /e "% 1" for Office 2010.
  4. Right Click on Command, choose "rename", and add something to the name (for example 2 (command2))  
  5. Go to HKEY_CLASSES_ROOT/Excel.Sheet.8/ shell/Open/ ddeexec
  6. Right Click on the folder ddeexec, choose "rename", and add something to the name (for example 2 (ddeexec2))
  7. Go to HKEY_CLASSES_RO OT/Excel.Sheet.12/ shell/Open/command 
  8. Double Click on (Default) and write "C:\Program Files\Microso Office\Office12 \EXCEL.EXE" /e "% 1" for Office 2007 or  "C:\Program Files\Microso Office\Office14 \EXCEL.EXE" /e "% 1" for Office 2010. 
  9. Right Click on Command, choose "rename", and add something to the name  (for example 2 (command2)). 

No restart is needed. Excel will now open a new instance for each file opened. I have found that opening mulple .csv files will stay in the same instance, but all .xslx files will open in their own instance.