error message; Your entry cannot be used. An integer or decimal number maybe required.

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A work sheet (only one of mine as far as I can see, (excel worksheet 97-2003) also tried saving as Excel worksheet general.... when I try and change size in print preview is giving me an error message :Your entry cannot be used. An integer or decimal number maybe required. Tried safe mode, nada, tried repair from disk,nada tried deleting HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Excel\Options from registry as was a soution that worked for someone, nada (so restored back up of registry) Now I'm stumped. Any ideas from ye who know?

No accessibility features turned on

I have XP so dont think regional settings are the answer either. they seem fine, don't really understand that answer.