Can't open Activity Monitor, System Pref

[silverhand31]

My friend's Mac pro (2008) got this problem.
Every time he open Activity Monitor or System Preferences, It's auto close the apps, could It be a virus?
Also his Mac now is hot like hell, and we can't even figure out what process is using high CPU usage.
What could we do now?

 

[simsaladimbamba]

Not a virus:

There are currently no viruses for Mac OS X in public circulation, only a handful of trojans and other malware, which have to be installed manually via entering the administrator password.
The only anti-virus you need to protect your Mac is education and common sense.
Also know, that the term "virus" is often used to refer to other kinds of malware, but there are differences, which you can find out by reading the following:
Mac Virus/Malware Info by GGJstudios​

To see, what process hogs up the CPU, you could use the iStat Pro widget.

Go to Macintosh HD / Users / FRIEND's USER ACCOUNT / Library / Preferences and delete com.apple.ActivityMonitor.plist and com.apple.systempreferences.plist and see, if that helps.

Btw, what Mac OS X version is the MBP using?

Identify your Mac and Mac OS X version, visualised in a more elaborate image
Identify your Mac and Mac OS X version using this 25 second video tutorial (3MB, .mp4, H.264)​

 

[silverhand31]

Thanks bro, trying it now