unable to open 'onenote'

Hi, thanks in anticipation for any help given in this problem.
I have a 2T drive, partitioned equally, on one I have Windows 8.1 OS (64bit) installed and the other, Windows 7, (again 64 bit). This may seem strange but I was experiencing problems in running FSX on Windows 8.1 and decided to revert back to 7, so the sole use of the windows 7 drive is to run FSX.
I have Office 365 running on both drives, and seem to run okay except for 'Onenote', it runs okay in 8 but when I try to open it in 7 I obtain the following error message.

C:\Program Files\Microsoft Office 15\root\office15\ONENOTE.EXE

'The version of this file is note compatible with the version of Windows you're running. Check your computer's system information to see whether you need x86 (32 bit) or x64 (64 bit) version of the program, and then contact the software publisher.'
As I mentioned earlier both systems are 64 bit and the program opens on Win 8, I have even tried installing and running the free version on the Win 7 drive.
Thanks
Jim

Yeah, tried that, the facility started, then 'stopped working' almost immediately, tried the process again but doesn't open again? Seems odd that Excel, Word and the others open okay? Really don't understand the problem, particularly as the Free version doesn't work either, but all works okay on the Win 8.1 drive. (mutter! mutter! mutter! LOL)

Hi, Yes, I did try that, one of the first things I did. I contacted a 'chat techy' at Microsoft, he suggested That I couldn't do it because I had MS Office installed, not sure if he got the point, but couldn't be bothered to pursue it.
I have since uninstalled the office program completely and downloaded a new copy of Onenote, works okay, brilliant program, not sure what I did without it up till now!
Many thanks for your help, vry much appreciated .
Jim

simmyjiff said:

downloaded a new copy of Onenote, works okay, brilliant program, not sure what I did without it up till now!

OneNote is the only part of Office I really want. I found a retail copy of OneNote 2010 -- nothing else -- on sale for $18 and snapped it up, just in case I really need to install it on another system, I have it up my sleeve. It's the only Microsoftware I buy - repeatedly.