Fatal Error when updating

[artician]

I ran into an issue with NGUI, but decided to update before posting about it. 

I was updating to the latest version from the asset store, and upon attempting to Import the latest version, Unity crashed immediately and I received this dialog:
----
Fatal error!

type == kMetaAssetType & pathName.find
(library/metadata") !=0
----

Can you tell me what this is? 
Also, can you tell me if there is a "proper" way to import a new version into an existing project?  (assuming this was my fault)

EDIT: this is preventing me from continuing work.  I deleted the NGUI directories and I still receive the above error when attempting to open Unity.

Thanks.

[beermoney]

are you sure its an isue with NGUI?
http://lmgtfy.com/?q=type+%3D%3D+kMetaAssetType

[artician]

Yes, yes it is caused by NGUI.  Thanks for asking.

[ArenMook]

Current version of NGUI requres Unity 4.3 or higher, as mentioned in the release notes. You can't obtain it from earlier Unity versions. You had to have used Unity 4.3 to download the package to begin with. You can obtain 3.6.0 b1, which was the last version to support Unity 3.5.7 by sending your OR# to support at tasharen.com.

[artician]

Thank you.  I think the issue I ran into is that while the individual pages on the Asset Store helpfully flag tools if they aren't compatible with your version of Unity, the "my packages" display section does not, and I generally update from there. 

Thank you!