Mariann789, when you download from third party sources, you always risk getting a tainted copy. Instead, follow the workaround in this article and download the ISO directly from Microsoft. This way, you can be assured you are getting a genuine ISO. Also, large files such as Windows ISOs can get corrupted during the download. Therefore, I would recommend that you go to MSDN Subscriber Downloads and find the SHA1 hash for the matching version of Windows to verify the ISO. When you find the correct entry, click on the "Details" link and look for the SHA1 hash.
BTW, you won't be able to download anything from MSDN unless you are a paid subscriber.