The cause is probably a corrupted download. I had the same thing happen.
Re-downloading resolved it.

--
Charlie.

Chris H. wrote:
> Joe, you should post your issues to the microsoft.public.onenote
> newsgroup. Before you do, take a look around previous posts and do a
> little search. I seem to recall a solution for this issue being
> posted.
> "Joseph di Piazza" <dipiazza@sprynet.com> wrote in message
> news:O38UAs7lEHA.236@TK2MSFTNGP10.phx.gbl...
>> Folks,
>> 1. After downloading the trial version of OneNote, I clicked on it,
>> only to
>> find the ominous msg: "OneNote.exe is not a valid Windows 32
>> application." 2. Was not OneNote to be useable even with a mouse on an XP
>> notebook?
>> Indeed, I want to try it out there while I get hardware fixes on my
>> Tablet.
>> 3. The size of the download turned out to be only 64 megabytes, when
>> I believe it was supposed to be much larger. Is the problem that
>> many bytes were lost in the download ( I was forced to use a dial-up
>> download, where poor or incomplete downloads often occur). [ Oh,
>> next time I could try a T-Mobile hotspot with T1 speeds; 4. but will
>> I have to delete the old download first since the new one may detect
>> it and complain that I am trying
>> to get a 2nd 60-day free trial. I am already 15 days into the trial,
>> for which I had to tell my life story. There was no report in "Add
>> or Remove Programs" in Control Panel of the presence of OneNote, so
>> I cannot uninstall
>> the download properly: 5. will this lack of an uninstall mechanism
>> lead to problems now or down the line?]
>> Whatever tips you all can offer, I'll appreciate greatly. 6. Should
>> not a dial-up download work ?
>> Joe