Can't save worksheets anymore

[Lesq]

I have a Windows 7 machine on which I successfully ran Excel 2003. I have some bespoke software that drives Excel via OLE. I upgraded to Office 2010 (leaving Office 2003 on the machine) and everything went to worms. Nothing worked properly.

I uninstalled Office 2010 (reverting to Office 2003) but now I can't save any of my Excel workbooks! Even worse, I can't trigger my Excel macros via OLE from my bespoke software now?

I've tried repairing, and re-installing Office 2003. Nothing makes a difference.

PLEASE!! Has anyone got any idea how I undo myself from this Office 2010 fiasco?