OptiPlex 745 can't open a Zip

The archive is corrupted and the hard drive is likely physically damaged.

That such methods is more effective that others, but if you can't repair zip file by ordinary ways, then google say to read that

http://www.wikihow.com/Use-Winrar-to-Fix-Corrupted-RAR-and-ZIP-Archives

http://kb.winzip.com/kb/entry/126/

You may repair zip file on following articles, guides, tips... http://www.win-rar.com/faq.html?&L=0

I advise against WINRAR as its a Virus Magnet and vulnerable to many exploits.

The WinRAR vulnerability can be easily exploited by remote attackers to compromise a Windows machine on which it is installed.

The remote code execution (RCE) flaw. The flaw can be used by an attacker to insert a malicious HTML code inside the “Text to display in SFX window” section when the user is creating a new SFX file. WinRAR SFX is an executable compressed file type containing one or more files, capable of extracting its own contents. “The issue is located in the ‘Text and Icon’ function of the ‘Text to display in SFX window’ module,” Vulnerability-Lab explained. “Remote attackers are able to generate own compressed archives with malicious payloads to execute system specific codes for compromise.”

As soon as the user clicks on a compromised SFX file, it starts functioning giving users no room to identify or verify if the compressed executable file is a genuine WinRAR SFX module or a compromised one. Requiring low user interaction without privilege system or restricted user accounts, successful exploitation of this vulnerability could compromise a user’s machine and network. All that is needed for it to work is a victim to open the booby-trapped file. The vulnerability has been tagged as “High Severity” and is yet to be patched.

7ZIP works fine.

https://www.7-zip.org/download.html