7 ultimate calculator miscalculating

I had home premium on my laptop and decided to upgrade it to ultimate (win 7 of course). Wierd thing and I can't say if it is from home premium as well, but since having ultimate on the laptop the calculator counts incorrectly.

I'm wondering if anyone has experienced this, if it is a virus (as no virus protection I have setup reads any danger).

How does one go about correcting something like this?
I don't even know what kind of information to post to get help with the issue.

you know i'm not that good with numbers, but lets say I add two and three digit numbers, the sum comes out off by a hundred or so as compared to doing long math by hand. I might not know calculus, but I can add. the calculator counts wrong

i was adding up bank account problems.
i swear i was in the green, it says the red.
i added up my purchases to my balance, i got a figure 100 to the red with the calculator and less than 30 to the red by long math.
i double checked it, i tripled checked it in case it was a late night vision thing.
no, it counts wrong in the double and triple digits numbers.

obviously this doesn't help my bank account issue. boo!

no simple numbers like 1-10 or 20 or so it does just fine. but once i've entered seven or so double or triple digit numbers, the calculation is incorrect.

can i post a desktop recording and images? i can white out the bank info, i don't think it shows in the recording save the figures.