Hello pammi1,
Not all licenses and installations of Office Home and Student 2010 are valid for three simultaneous installations.
If you purchased a genuine full retail packaged product from a legitimate retail store, or pourchased a downloadable version online from Microsoft or Dell (any other source AFAIK is nongenuine), that product key and license is good for three simultaneous
installations. However, if you are trying to activate a peinstalled installation of Office H&S 2010 with that product key, and it's not working with an error message along the lines of "not valid," that means you are trying to activate an OEM installation
of Office with a retail product key.
On the other hand, if you purchased Office H&S 2010 in the form of a product key card package, then that product key and license is good for one computer only.
So if you could supply more detail about what you bought and the types of installations that are not accepting the product key, that would be good. But, don't post any product keys!
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