I try to install Complete MiKTeX 2.9 But there is this:

Error: The operation could not be completed because the following file failed verification:

C:...\mikTex\toptesi.tar.lzma

There is the same with the basic version.

How can I solve my problem?

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I have the same problem. It seems that it occurs no matter which mirror I choose. –  John Peter Thompson Garcés Nov 10 '13 at 20:07