Installing Software, etc for Mac

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Hi mate,

I never use Mac so I don't know about it at all. One of my friends informed me his problem but I couldn't help him:

"He want to install Anti-virus on his computer (Mac OS), but every time he click the set up, it goes to SWF player instead of begin the installation. The same happened when he want to install any software.

Also when he download any file from forum, etc; the file goes to SWF player when he opened it".


To Friends here who are familiar with Mac, may I ask for help how to fix this?

Thanks in advance!