Q: I think my imac has a virus, whats the best software to check and erase the virus, please

There are no know viruses for Mac.  There could be malware or adware that could have be installed.  Download and run Etrecheck.  Copy and paste the results into your next post. It's a diagnostic tool that was developed by one of the most respected users here in the ASC.

The Safe Mac » Adware Removal Tool

Helpful Links Regarding Malware Protection

An excellent link to read is Tom Reed's Mac Malware Guide.

For adware removal see The Safe Mac » Adware Removal Guide and The Safe Mac » Adware Removal Tool.

Also, visit The XLab FAQs and read Detecting and avoiding malware and spyware.

See these Apple articles:

  Mac OS X Snow Leopard and malware detection

  OS X Lion- Protect your Mac from malware

  OS X Mountain Lion- Protect your Mac from malware

  OS X Mavericks- Protect your Mac from malware

  About file quarantine in OS X

If you require anti-virus protection Thomas Reed recommends using ClamXAV. (Thank you to Thomas Reed for this recommendation.)

From user Joe Bailey comes this equally useful advice:

The facts are:

1. There is no anti-malware software that can detect 100% of the malware out there.

2. There is no anti-malware that can detect anything targeting the Mac because there

     is no Mac malware in the wild, and therefore, no "signatures" to detect.

3. The very best way to prevent the most attacks is for you as the user to be aware that

     the most successful malware attacks rely on very sophisticated social engineering

     techniques preying on human avarice, ****, and fear.

4. Internet popups saying the FBI, NSA, Microsoft, your ISP has detected malware on

    your computer is intended to entice you to install their malware thinking it is a

    protection against malware.

5. Some of the anti-malware products on the market are worse than the malware

    from which they purport to protect you.

6. Be cautious where you go on the internet.

7. Only download anything from sites you know are safe.

8. Avoid links you receive in email, always be suspicious even if you get something

    you think is from a friend, but you were not expecting.

9. If there is any question in your mind, then assume it is malware.

Nothing you have described would indicate that you have any sort of currently known malware infection, so you should not jump to that conclusion.

It does sound like you may have accidentally installed some Adware which is common today and Kappy has provided you with a link to the best tool available for eliminating that.

Please post a screenshot that shows what you mean. Be careful not to include any private information.

Start a reply to this message. Drag the image file into the editing window to upload it. You can also include text in the reply.