Google Drive terminates without error on startup

I've used Google Drive for awhile now, but it won't start up after installing on my latest system re-build. I'm still using the same OS, hardware, and basic software load (antivirus, firewall, etc.) that I have for years during which I had not previously had problems with Drive.

OS: Windows 7 Ultimate x64
Google Drive Version: 1.12.5329.1887

Now, whenever I try to run Google Drive, it just spawns two instances of the executable which die shortly after. No error messages are posted to the desktop, and nothing indicating any problem is written to the Event Log.

After some research, I've yet to find anyone having the same problem who's found an answer. I did find out how to run Google Drive in diagnostic mode, using the --vv parameter at the command line. After that, I opened up the sync log and got this:

2013-10-31 17:11:24,039 INFO pid=3664 1892:MainThread      logging:1600 OS: Windows/6.1.7601-SP1
2013-10-31 17:11:24,039 INFO pid=3664 1892:MainThread      logging:1600 Google Drive (build 1.12.5329.1887)
2013-10-31 17:11:24,039 DEBUG pid=3664 1892:MainThread      logging:1608 DEBUGGING DUMP is ON.
2013-10-31 17:11:24,051 ERROR pid=3664 1892:MainThread      logging:1575 ERROR, UNEXPECTED EXCEPTION
2013-10-31 17:11:24,051 ERROR pid=3664 1892:MainThread      logging:1575 [Error 5] Access is denied
Traceback (most recent call last):
  File "<string>", line 232, in Main
  File "<string>", line 118, in RegisterCustomFileTypes
  File "P:\p\agents\hpal4.eem\recipes\353983091\base\b\drb\googleclient\apps\webdrive_sync\windows\build\pyi.win32\main\outPYZ1.pyz/windows.registry", line 62, in GetValue
WindowsError: [Error 5] Access is denied
2013-10-31 17:11:24,052 INFO pid=3664 1892:MainThread      logging:1600 Crash reporting disabled. Ignoring report.
2013-10-31 17:11:24,052 INFO pid=3664 1892:MainThread      logging:1600 Exiting with error code: 0

I'm running on an account with Administrator-level permissions, and have even tried using "Run As Administrator" on the EXE. I'm not sure why it's looking for a P:\ drive, as no such volume has ever been mounted on this system.

What should I do to try to further troubleshoot, and resolve, this issue?

The solution of @pestul didn't work here. Even with diagnostics mode (C:\Program Files\Google\Drive>googledrivesync.exe --vv), the app failed to start.

So I deleted the C:\Users\*username*\AppData\Local\Google\Drive folder and the app started again. Of course you will have to re-enter your credentials and start the whole sync process from the beginning BUT the new GoogleDrive version (1.18.7821.2489) doesn't force you to start with an empty folder, meaning you can point to the old folder AND it now detects if the local files are the same on the server, eliminating the need to synchronize everything from scratch!

As an example, it took approximately less than 5 minutes to synchronize my 13.31GB folder with 60.063 files in it. In the middle of the process it will show a popup window telling you the number of files that exist only locally, the number of files existing only on server, and the number of files conflicting.

I FIGURED IT OUT! At least for me that is.

See if this is the case for everyone. Windows Firewall and Advanced Security. Under the 'inbound rules', if you see a one or two block 'chrome.exe' rules. Disable both of those rules. I then ran diagnostic start again for Google Drive and it worked straight away! You may not even need diagnostic startup, it may just work.. or I hope this works for everyone.