strange error while creating atlas

[venusboysatish]

I have been using NGUI for a couple of months now, and found it really useful ...  Except when it fucks up out of nowhere. I am getting the below two errors in the unity console while creating an atlas.

'Assets/Art/MainMenuArt/ MainMenu.mat' is not a valid asset file name.
UnityEditor.AssetDatabase:CreateAsset(Object, String)
UIAtlasMaker:OnGUI() (at Assets/NGUI/Scripts/Editor/UIAtlasMaker.cs:769)
UnityEditor.DockArea:OnGUI()

UnityException: Creating asset at path Assets/Art/MainMenuArt/ MainMenu.mat failed.
UIAtlasMaker.OnGUI () (at Assets/NGUI/Scripts/Editor/UIAtlasMaker.cs:769)
System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) (at /Applications/buildAgent/work/b59ae78cff80e584/mcs/class/corlib/System.Reflection/MonoMethod.cs:222)

any one faced these errors before? any known workaround? i am unable to create any atlas anywhere

in moments like these i dont curse ngui but have it out on unity tech for their crappy gui in an otherwise awesome engine.

[venusboysatish]

ohk, i fiddled around and it started working again.
i opened the folder properties of my unity project root and unchecked the read-only, before hitting apply.
i am not sure if this fixed the issue, but its working now.