Reply to Problems with .zip files from Native Instruments!!

So here's the story guys, when the new Traktor 2.5 was released I downloaded it from from the service center however after a suspiciously quick download in which the .zip file was said to have completely downloaded, I open the file using winzip (& later 7zip) to revel a message saying "cannot pen file: it does not appear to be a valid archive. If you downloaded this file, try downloading the file again." which I did through both the service center and the update manager in the NI site (using igetter), I later realized it wasen't only the update it was all the .zip files that came from NI. Ultimately I uninstalled the old Tracktor I had (since this error only occured to .zip from NI) and tried redownloading the file yet again but the same error occured.... can anyone help me ressolve this unusual problem?!?!?!