Once again Payl. Go away, your sarcasm is of no help.
I don't need any computer specs to say that I have had McAfee (installed on the computer when I purchased it) and while I used it for the first free year, it wanted to block anything and everything even Digital paintball 2. I remember the same error as you have described happening when I tried downloading from sourceforge. Don't pay any mind to this and do what Chemical suggested and use the download link provided on this site.
However, on the computer crashing part. This has also happened to me. On two occasions it was due to a bad video card.
-My first card was not good enough to run the program (which doesn't sound like the problem since, as you said you have played the game with the same computer before) Jitspoe might have a page somewhere describing computer specs for running his game... idk you'd have to find it and compare the specs to your device.
-My second card's fan broke and would over heat. Cards can also be clogged with dust and debris, so try using an air canister to blow the excrement out. And if the fan isn't working on it, it's time for a new card all together.
If you have an Nvidia card, try running this program (
http://www.evga.com/precision/ ) and have the video card's fan speed turned up. Most cards only run at 40% maximum speed for some reason unless it starts to heat up. Avoid that and turn it up manually with the program.