I'm having a problem downgrading my BB 8330 from version 4.5 to 4.3. I've tried reading several posts on this issue but nothing seems to work. Is there a simple breakdown of instructions that actually work? I would really appreciate some help here. I'm using Desktop Manager 4.5.0.16 and my OS version is 4.5.0.131. I'm trying to install the older 4.3 version to get my Roaming Only feature back. Thanks for any help anyone can provide.

Wirelessly posted (Tmo's cheapest BB customer)

Might help if you elaborate where you are running into problems. Right off the bat though, did you uninstall the OS4.5 from your computer? Did you remove the vendor file for OS4.3 when you installed it on the computer?

Well when I connect my blackberry to my computer via USB cable, it doesn't allow me to view anything on the blackberry phone itself. It doesn't show applications, OS or anything else. I can't uninstall what I can't see and I'm scared at this point to attempt to uninstall without knowing how to reinstall the 4.3 OS. Hope this helps. I'm a dummy when it comes to these things.

Here are the instructions in the FAQ:
How do I downgrade the OS on my BlackBerry? - BlackBerryFAQ

However, the new Desktop Manager does not downgrade automatically, you have to tell it to install the old OS and then it'll warn you that it is an older version. To which you just approve that.

You generally do not uninstall the OS, it is closer to overwriting it with the other version. To uninstall it, you would use JL_Cmder to wipe the device then install the OS. However, you don't generally have to wipe the device, you can just install the OS you want and Desktop Manager will remove the old OS itself as part of the install process.

Before you do that, I'm not sure what the roaming only feature is, but are you sure the new OS doesn't have it or it can't be activated again?