In Excel 2007 I found an option to 'Show all windows in the Taskbar' under
Excel Options- Advanced - Display... Select it to solve your problem.

Which version are you using?

"David Blaine Fullerton" wrote:

I feel Excel should allow you to open new spreadsheets into separate windows
just like Word does. Then, you can manipulate them easily. I hate to open
different spreadsheets into the same Excel window. Yes, I understand how to
work around this, but it is painful when you want to Cut & Paste between two
different spreadsheets, then I have to keep opening a new Excel, FileOpen,
find the document, etc. Very insane. Needs to have an option in Excel
settings to work around this problem.