familiarize yourself with what a virus is and what it isn't. At most Claro-search.com could be classes as a search hijacker.
Since it is a search engine that many use by choice (see for yourself at http://www.claro-search.com/ ) it is often offered as an included download that you can AT YOUR OPTION install with the utility you actually wanted. During installation, YOU, the installer, can easily opt to NOT install the additional software but there is the assumption that you are paying attention to EXACTLY what you are doing rather than blindly clicking buttons. Yahoo, Ask, and Google as well as Bing all do the same thing and are offered up in the same way.
Here is a handy link demonstrating how to remove it if you don't want it -
As a teacher you should be instructing your students to pay attention to what they are doing at all times (attention to detail) AND you should test things before assigning them to be done by students. For instance if you had gone to download.com and searched for ERASER you would have got this page and the green download link is a direct link:
If you had the students look at the ERASER page here http://download.cnet.com/Eraser/3000-2092_4-10231814.html?tag=mncol;5 you would be seeing the green Download button which also indicates that it is CNET Installer enabled and has a handy little Info icon that tells you about the offering of additional software. Then just below that green download button it doesn't even take a really sharp eye to see the words DIRECT DOWNLOAD LINK
You do not mention what you teach but let us hope that it is not computer science at ANY LEVEL!
This is an alert, question, and rant! At my direction (!), my students downloaded the Claro Search virus from CNET downloader while installing some other software (Eraser). They use Chrome. They have deleted browser add-ons installed by Claro, de-selected Claro as the default browser, and run Malwarebytes. Apparently Malwarebytes did not detect the virus, though other forums have recommended it as fixing the problem. Students have been unable to uninstall Claro: it still shows up in the Windows 7 uninstaller program list. Also, there is concern about what Claro is doing behind the scenes since they are unable to delete it. Any advice on how to get rid of it for good, including from the list of programs in Windows 7 uninstaller? Any knowledge about what malicious activity Claro may do, aside from being hard to get rid of? For the rant part, I'm so disappointed in CNET and will no longer direct students to this site, or download software from it myself. I am embarrassed that I have been telling students for some years that CNET is a safe site to download software. Why would CNET allow software like Claro to be bundled in the Downloader?