Worksheet Divides Everything by 100

Hello

Im having a confusing problem which im failing to figure out.

Every worksheet that I use divides all the values by 100, ive tried changing the formating but this dosent work, ive also replaced the worksheet template but this didnt work. Then I reinstalled Excel and that didint work.

I now fear that a virus has got itself into my Operating System, but it only affects Excel and everything else works fine.

Please help

Paul