My iMac has started to act strangely. Is there a good app for diagnosing problems or malware?

[iMore Question]

The screen freezes more frequently 2 or 3 times a session, when it used to be very infrequent. In the past I'd "force quit" with no problem, now more frequently the screen just freezes, and I have to reboot. This happens with mail, with Safari and Pages. I also use Word and XCEL and they are 'buggier' than in the past.

 

[anon(9602380)]

The screen freezes more frequently 2 or 3 times a session, when it used to be very infrequent. In the past I'd "force quit" with no problem, now more frequently the screen just freezes, and I have to reboot. This happens with mail, with Safari and Pages. I also use Word and XCEL and they are 'buggier' than in the past.

1. Here is a link to an app that will remove adware & malware from your Mac if that is the issue. Was originally called Adware Medic and is now called Malwarebytes Anti-Malware for Mac.

2. Another thing to check would be how full your HDD is. If your HDD is almost full, this could be the cause.

3. Could also be that your HDD is beginning to fail.