Installed to Program Files/Sony/Vegas Pro 12 and previous versions, 10 and 11, sit just above in Program Files/Sony. I uninstalled and reinstalled. Didn't help. I'm running Windows home premium 64 bit on a Dell i7.

Sounds like a bug.
Report to Sony using the links at the top of this page.

Thanks for that. I emailed SCS_AU_Support@am.sony.com so we shall await their response.

Cheers...

Did you install any 3rd party filters?

Try downloading the installation package again.
One and only once I got a messed up package and downloading it again fixed the problem.

I know, I know, everything in the entire process is checksummed within an inch of its life but it happened to me and a couple of others here. This probably isn't the problem but it'll only take a few minutes to do another download and if that is the problem and you didn't try this you could be chasing a ghost forever.

Bob.

Did that, thanks Bob. Didn't help.

Nothing else installed, LightAds, other than the file as downloaded from Sony.

The problem dialogue box does not always appear. I've been fooling around with it now for too long and I can find no rhyme nor reason for it.

Here's the info that appears relative to the problem:

Problem Description
Application Name: Vegas Pro
Application Version: Version 12.0 (Build 367) 64-bit
Problem: Unmanaged Exception (0xe0434f4d)
Fault Module: C:\Windows\system32\KERNELBASE.dll
Fault Address: 0x000007FEFD74CAED
Fault Offset: 0x000000000000CAED

Fault Process Details
Process Path: C:\Program Files\Sony\Vegas Pro 12.0\vegas120.exe
Process Version: Version 12.0 (Build 367) 64-bit
Process Description: Vegas Pro
Process Image Date: 2012-09-14 (Fri Sep 14) 00:31:36

Just to put closure on this (at least I hope it's closure) I have been working with Sony support in the form of Justin Moy, New Magic Australia Pty Ltd, who was most helpful and attentive and we now have Vegas 12 up and running; the offensive dialogue box nowhere to be seen.

And now, I am happy to say, Vegas 12: nice.

Cheers.

John, glad your problem is fixed. Unfortunately, I still get that message box sporadically---can you share anything that helped get rid of it?

Ha ha, good question! Here’s what Justin asked me to do:

‘Can you please try creating a new user account and install Vegas Pro 12 on the new account.’

So I did and the dialogue box did not appear. But as I said to him that’s a work-around and not an acceptable solution.

Then he suggested I try this:

Here are some steps you can try on the current user account then: 
1.       Delete the folder located C:\Users\<USER NAME>\AppData\Local\Sony\Vegas Pro\12.0
2.       Reinstall the latest version of QuickTime
3.       Reinstall latest graphic card drivers

Which I did none of which seemed to make any difference. I even did a system restore to a very long time ago and installed Vegas 12 on that. Didn’t help. I undid the system restore, and in the meantime Windows update installed new software. I added and deleted a couple of other programs as one does, and lo and behold one fine morning the offensive dialogue box was not there, and still isn’t, touch wood. I accused Justin of doing long-distance magic which he would neither deny nor confirm so frankly I’m none the wiser but the good news is the problem no longer exists, at least for now.

Wish I could be more helpful, Cold Ones, and truth to tell I kind of expect to see that damned dialogue box rear its ugly head at some time in the future. In the meantime it’s happy editing!

Cheers.

FWIW, just updated to build 394, problem still persists. Here's SCS support suggestion:

Lets have you install the SCS application to a newly created administrator profile. This will require uninstalling the software, creating a new user account, logging off the old user account and logging onto the newly created administrator account, then installing and activating the app on the new administrator account. This allows the software to make the necessary changes needed to the registry. Please consult the Help and Support Center in your Windows operating system for specific directions regarding creating a new user account with full administrator rights.

Go to Control Panel > Programs and Features and uninstall the SCS software if it is currently installed.

Now go to My Computer and browse to "C:\Program Files\Sony Setup" and delete the folders within.

Next, it's time to create a new user account with administrative privileges. Go to Control Panel > User Accounts. Select "Add New User" and type in a new name for the new user account. When asked what permissions level to assign to the account, select Administrator.

Then go to Start menu and choose "Logoff" or just restart the computer to switch users. Be sure to log into the new user account, reinstall the program, and register the application.

Once the application is up and running you can log back to your normal user account. Now go to Control Panel > User Accounts and remove the test account from your computer.

Didn't work for me, but perhaps one of you will catch a break.

Loads OK when I'm logged on as the other user but when I switch back the same old same old so that really didn't help other than perhaps informing Sony what might be going on.

1) Wipe your harddrive clean of everything on it.
2) Reinstall Windows 7
3) Get rid of user account control

A whole lot simpler to just use a specific user account!!

Problem solved.

Windows 7 includes ‘special’ folders including ‘my videos’. I had previously deleted that folder as the ‘my’ part of the name is redundant on ‘my’ computer. Seems Vegas pro 12 will not play unless it finds that special folder so instead of deleting it I renamed it to ‘videos’. Vegas now loads as it should.

Cheers.