XLSWrite works sometimes,, other times I have to re-run up to 5-6 times

This is the error code. Excel is NOT loaded into memory, i.e., is not open. Only Matlab is running: Command Window, Editor, Figure window.

"Error using xlswrite (line 220)
Error: Object returned error code: 0x800AC472

Error in SpectralRatioST (line 389)
xlswrite(newFileName2,HiSpike);"

I'm analyzing many data files. Every time, the first 350+ lines of my .m file run just fine. Sometimes the last lines that call XLSWRITE work very well for maybe 6 or 8 files, then I get this error message. I have to re-run my program up to 5 times (or more!) before XLSWRITE works properly. Today is a "bad" day -- the error happens frequently

Can anyone explain what is going on here, and, more importantly, how I can fix he problem?

Thanks very much

[Walter Roberson]

Duplicates http://www.mathworks.com/matlabcentral/answers/62391-xlswrite-works-once-then-i-get-error-code-0x800ac472