Mac App Store Error 100

Forgive me if this topic has been previously discussed, but for the past three days, I've been trying to upgrade from FCP7 and purchase FCPX from the Apple Store, only to receive an error message:
"We could not complete your request. An unknown error occurred (100). There was an error in the App Store. Please try again later."

After spending 2 hours on the phone with Apple Support, reinstalling my OS X Lion, deleting cookies and various cache folders, logging in/out, rebooting, etc., I am still unable to purchase anything from the App Store. However, I was able to download a free fcpx app.

I googled this topic and found in some cases this is a problem that dates back a couple of years.

I have a iMac 27" mid 2011, 8 GB memory, Radeon HD 6970M graphics, 3.4 GB Intel i7 processor, running OS X Lion 10.7.5 with all the latest updates including iTunes.

Some say the Apple Store may have been experiencing an overload of simultaneous download/purchase requests and their servers were perhaps overwhelmed.

Others say Apple's Term and Conditions were not agreed by me (I didn't get prompted for this), while still others say I must perform a total clean install of my computer.

I purchase music and apps regularly via iTunes and on my iPhone. The last download I received from Apple was an update to OS X Lion during Mar 2012.

Any thoughts or suggestions would be greatly appreciated and helpful. Thanks again everyone!

i had the same problem.

There had been some problems with the Apple servers over last week.
For me the problem was solved just by creating a new user. This way some cached files were not retrived by the store.

-Andreas

Thanks Andreas. A new user account might be the route I need to take in order to purchase FCPX. I didn't think it would be so hard to get FCPX.

I received a scheduled call from Apple support, but the call dropped out a couple of minutes into the call. They never called back. I tried the apple store anyway and this time I get a message that my credit card is declined. I verified my card and account info and all is correct. I even resubmitted all the info just to be certain. Tried again and got the same card decline message. Maybe a different card will work.

Logged out and shut down the computer and took the wife and kids out to dinner and a little shopping afterwards using the same card. No problem with my card. Go figure.

At this point, I can't do it anymore. I'll give it a couple of weeks before I try again. Frustrated to say the least.