Following are some of the reasons why it can happen:

1. Your virus protection program may have identified OfficeClip zip file as having some virus. We check our program for virus and also our exe and dlls are signed with secured key. Sometimes virus protection program makes false positive recognization.

2. Your service provider may have put some limits

3. Zip file is corrumpted. Download it again using a better internet connection and then check the sha1 code as in the download page

4. In rare situation this can happen if windows cannot display some font correctly.