Calculation and saving not working. Any idea?

[MrLutzie]

Hello,

I have an excel workbook that is refusing to calculate properly, and as a result it also will not save (As a calculation is done before each save)
Details;

1. It's fairly large, in the 50mb region, Excel 2010
2. No external links to other workbooks.
3. Thousands, if not millions, of formulas. Most are vlookups, and nested IF functions (up to 5 levels). Also has a couple of dozen pivot tables.
4. Calculation is not automatic by default; making any alterations would cause a fresh calculation run, which leads to point 5.
5. Due to size a full calculation run takes about 40 seconds on an i7 CPU.
6. Has worked for previous 3 months work.
7. Theory is several data sets are added into sheets inside it, then several other sheets use this information to determine what I need. So it's a "shove a load of data into it, hit calculate, and there's all of your answers"

When manual calculation is run it goes through the whole process Calculating: (8 processor(s)): 21% etc, but the Calculate option remains.
If I save, or save as... then the same thing occurs with a "Document did not save", and I've double checked through Windows Explorer, and it's true, nothing has saved.

Any ideas?

Thanks,

Stephen

[:) Sixthsense :)]

One suggestion may be helpful or may not try to save in xlsb format if possible.