A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
I can open two workbooks in Excel 2010 and either copy whole rows or just a range of cells, copy and then in the other workbook I can "Insert copied cells". If I do this with a cell range, I get promtoed to move existing cells down or right to get out of the way.
So this does not reproduce your problem.
However, if I open a workbook from an email attachment without bothering to save it locally first, and copy cells from there I can't insert them in another workbook.
Except... if you notice the information bar in Excel for the attachment workbook it says "this file originated as an e-mail attachment and might be unsafe". There is a big button to "enable editing". If I click this, I can now copy data from here and insert into the other workbooks as before.
Does this work for you?
Adam Vero MCT, MMI, MBMSS:CRM 4, MCSA:Messaging http://www.meteorit.co.uk