Excel 2007 :: Workbook Appear To Be Open But Can't See Anything

I am using Excel 2007 on Windows XP professional.

The workbook is called EA.xlsm, and contains dozens of charts, tables and pivot tables - all of which pull their data from external files in the same folder. In case it matters, the folder also contains a Word 2007 document which contains embedded charts form the EA.xlsm file and lays them out for printing.

My problem is that all of a sudden, when I try to open the EA.xlsm file, it gives me two consecutive error messages, as follows:

Microsoft Office has identified a potential security concern.

File path: c:My DocumentsEA.xlsm

Data connections have been blocked. If you choose to enable data connections, your computer may no longer be secure. Do not enable the content unless you trust the source of the file. [Enable] / [Disable]

to which I click enable, and then....

Microsoft Office has identified a potnetial security concern.

File path: c:My DocumentsEA.xlsm

Automatic update of links has been disabled. If you choose to enable automatic update of links, your computer may no longer be secure. Do not enable the content unless you trust the source of the file. [Enable] / [Disable]

to which I also click enable.

Excel then opens, but I just get the program with a blue screen. i.e. it looks like you have opened Excel, but not opened a file yet. However, if I try to close Excel, it asks me if I want to save changes to EA.xlsm, and if I try to open EA.xlsm again - it tells me that it is already open. Also, if I press Alt+F11 to open the VBA console - I can see the names of all of the sheet tabs in the file - but when I close the VBA console, it looks as though I do not have a file open again.

I suspect that somehow, somewhere the file is open, but I dont know what I need to do to be able to see/edit it. Or even worse - if it has become corrupt. It would take me about a month to put this file back together again from scratch.