I am unable to use the trial version?

I am working on a fairly new computer, and to my knowledge (and I am the only one using the machine) I've never had Trados installed on it. Your product was recommended to me, and so I installed the trial. The installation went well, I got a prompt to update to the latest version, which I did and then the program opened.

However, every time I try to translate a document I get an error that a number is too great for an INT16 - which according to Google means that I have an invalid licence. 

So when I checked, I can see that my product is activated, but I am not able to deactivate it, not even offline. Uninstalling and reinstalling made no difference. What else can I try? If this is a problem with the software, I am not comfortable spending all that money to find out it's not compatible with my computer? I am running Windows 8.1.