Problem viewing a Google embedded spreadsheet

pms7

Not sure if this is the right place for this..
Have two websites with an embedded Google spreadsheet which has been working fine for a year. Now some people can't see the sheet. This message comes up when click on a link to printer friendly version of the sheet on the site.

This content cannot be displayed in a frame
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I have moved to Skydrive Excel sheets as a temporary measure, but it would be easier to keep things as they are. The sheets are shared for public viewing. Is this a temporary Google glitch?