The product distribution file could not be verified. It may be damaged or was not signed.

Thanks to Grey Day and all. A combination of turning Virus Barrier off, trashing the C folder, and reinstalling the OS X 10.7.4 Combo update finally did it.

Now running 10.8 on both MBP and MP. Thanks again.

Ryan2004aapple-- just to set the record straight... booting in safe mode did not work for many of us. Also- I assume "entering code" refers to typing a file folder name to locate a folder???? I'm glad rebooting in safe mode worked for you.... please don't scold us.

Well i apologize that it did not work for you. I fix appl computers for a living and simply booting into safe mode as worked alomst every time. And its not called scolding, its call encouraging. I was simply encouraging people to try safe mode since it wasnt even stated on the first page. Booting into safe mode will automatically turn off any and all virus protection as well as boots up the bare minimum to launch the system. Out of the 100+ computers I have seen with mt lion issus based on this case, safe mode has fixed 94% of them.

So again, sorry it didnt work for you, but if my post was not directed directly at you, was not necessary for a reply from you. And please do not speak for the compunity. Everyone has their own voice. Your not their advocate. If it didn't work for you, great. Move along to the next post!

Restarting in the safe mode worked perfectly for me. I had no trouble installing Mountain Lion whereas I was not able to do it before. Thanks very much.

It's too bad the idiot I talked to at Apple Support didn't suggest this. The suggestion I got from him was to take my computer to the Apple Store and let them take a look at it there. I would expect something like this from a Windoze idiot, but not Apple. They'd better watch out, or they'll end up in the world of mediocrity, just like everyone else if they're not careful.

Booting into safe mode did the trick!! Thanks!

Deleting the C folder fixed it for me, wondering if it's worth this hassle. Thanks

flyboy _ followed your advice on downloading easyfind, located com.apple.appstore, highlighted all - deleted, turned VirusBarrier off and now works like a charm. Thanks for posting your advice here!!

Great! Thank you for the hint

im new to posting and kinda new to fault finding as mainly just an end user but I found a problem downloading Mountain Lion and the message said 'Product distribution file error' so I was heart broken. I have a 3.4 ghz 27 inch IMAC and love the solid hard drive and mad speeds but never thought something so trivial like downloading from the mac app store would cause so much s*it.

My problem started when the 3 dongle ran out of credit half way through the download, **** you 3 for not letting it finish and charging me after, what a waste of 2 very precious gigs before the download stopped.

Anyway, i was dubious about forums and only tried your advice when APPLE suggested going to purchases in app store and re-clicking the ML icon, which of course never worked and the APPLE guy never replied when I complained it did no work.

im in SAFE mode now and it is working? touch wood. Why the **** APPLE dont know this is beyond me?

my question is whats in the C file/folder that you deleted and then it worked. Will ML when trying to install in normal mode then fix that little C file so it dont cause more s*it or is it only that the C file was NOT letting ML load, it wont ever cause probs to other stuff I hope. should I do anything more!

Safe mode worked no problem

I turned VirusBarrier off, downloading easyfind, located com.apple.appstore, highlighted all and hit delete key. All but 3 files deleted. This solved the problem for me. Like you I did not want something else to be affected. So far all is good. In my case the problem started when I got a free downloaded for my Mac Pro. When I went to download on my desktop Mac that's when my problem started. Good Luck - Tom

I liked the ryan2004aaple's suggestion - two words - SAFE MODE. Start in safe mode (hold shift while starting until you see the apple and spinning gear. Then you see a progress bar indicating safe mode start. WORKED FIRST TIME just like he "guaranteed".

worked great thanks

Worked for me - thanks