[Albert62]

I don't think this has been released or found.. But I keep seeing people talking about that they deleted the vendor.xml file and they still can't update/downgrade their BlackBerries..
I saw the method in some threads that Elite1 gave:

How to Fix OS not Appearing as Available

If you're having this issue, there are 2 common reasons.

The first is that there is an extra copy of Vendor on your PC (assuming you've already deleted Vendor). Search your PC for Vendor. It might appear in Temp Files or elsewhere.
When deleting Vendor, always hold down SHIFT and press DELETE to permanently delete.

If there doesn't appear to be Vendor anywhere, you need to delete the contents of the AppLoader folder. (That's the folder where you found Vendor.)
Uninstall the OS: Control Panel>Programs and Features, highlight this BlackBerry Device Software, click Uninstall at top.
Delete AppLoader folder contents: Highlight any item, CTRL+A to select all, SHIFT+DELETE to permanently delete.
Restart PC.
Re-install OS on PC: Go to your browser's downloads section, double-click OS to start InstallShield Wizard.
Delete Vendor: Return to AppLoader folder, highlight Vendor, SHIFT+DELETE.
Load OS to BB: Attach BB to PC, double-click Loader (in AppLoader folder, where you deleted Vendor).

And it works for some people and it doesn't for others..

Well this is the method that always worked for me since DM6.1 was released..
Go to C:\Program Files (x86)\Common Files\Research In Motion\AppLoader (On 64Bit)
Go to C:\Program Files\Common Files\Research In Motion\AppLoader (On 32Bit)
Find vendor.xml, Open it in Notepad and erase everything
And put this in:

<vendorsrc version="0.0.0.0">

</vendorsrc>

That's all! Hope it helps
I really don't know if this has been released, so I guess credits goes to me, If not credits to him/her

[underway99]

Starting with the later OS6 releases, there are now three copies of VENDOR.XML

C:\Program Files\Common Files\Research In Motion\AppLoader (for 32-bit Windows XP/Vista/7)
==========OR============
C:\Program Files (x86)\Common Files\Research In Motion\AppLoader (for 64-bit Windows Vista/7)

C:\Documents and Settings\*name*\AppData\Roaming\Research In Motion\BlackBerry\Loader XML

C:\Documents and Settings\*name*\Application Data\Research In Motion\BlackBerry\Loader XML

You can also just search for VENDOR.XML. Make sure that you choose ADVANCED SEARCH and include hidden files. It should show the file in at three locations. Delete every copy that it finds.

[artic80]

I have been having problems at the office since all of the device running on OS7 and later OS6 does not seems to recognize any OS that I have installed. Even tried to uninstall and install the DM and the OS several times out of desperation. Could this thread is the answer to my woes and worries? I'll let you know tomorrow when I can access my pc at the office and several 9360 devices that waiting to be upgraded before I distribute it to my users but can not since the existing OS is eating up a full battery life in just 4 hours.

[artic80]

Hey, it turns out that it will create another vendor.xml file on your D:\Documents and Settings\Deploy\Application Data\Research In Motion\BlackBerry\Loader XML every time you plug in other BlackBerry device. Since I can plug and unplug as many as 6 different BlackBerry Device in a day, I was having trouble at it first. But now it's all good