Mavericks won't install, the button in App Store is blank and non-responsive.

Question

This is extremely frustrating, and I have read every website trying to answer this issue. None of their problems match mine.
I tried to download Mavericks yesterday. It appeared to download as normal, with the icon in launch pad, but the progress bar never moved. I cancelled the download, and tried to restart it. The download button is non-responsive. I've tried going to the store tab, clicking unfinished downloads, and it says all downloads are complete.
When I go to purchases, Mavericks is listed under "other downloads," but the button is solid black with no text, e.g. download or install, and is non-responsive. Clicking the button does nothing.
I have tried using CCleaner to clean the app store's cache, restarting the computer with a full shutdown, quitting and restarting App Store, etc. Nothing works.
If I close and reopen App Store after a full shut down, Mavericks will disappear from the purchases menu. If I go to Mavericks, click "free upgrade," then button changes to "install." When I click install, nothing happens. Mavericks reappears under the purchases menu with its button, again, completely black with no text. The button is non-responsive.
Having a $2,500 Mac, I have to say that I am extraordinarily upset with the shoddy work of Apple over the past few years. For $2,500 I expect the product to work.

Answer 1

Actually, it appears to have started downloading, even the the purchases tab still doesn't reflect it.
Try what I did, typing "sudo nvram boot-args="-x"" (include the quotations around the -x), and then entering your account password.
Reboot the system, which will cause it to do a full reboot (you'll find your mac operates very slowly). Log into your account, then try hitting "free upgrade" and "download" from the Mavericks page in app store (not the purchases tab). It will ask you for your Apple ID and password, then it *should* automatically take you to launch pad.
If the download doesn't seem to be progressing, press the icon in launch pad to pause it. Exit launch pad and scroll down in App Store to 'free apps" on the right side. Click to download one of them, enter your password and Apple ID as usual, and see if it downloads. Once finished, hit the Mavericks icon again to unpause it. It should start then. It's clearly a very large install, so over the past thirty minuites the progress bar has moved roughly a milimeter.