Error building asset bundles in Unity 4.5

I recently upgraded my project from Unity 4.2.1 to 4.5.0 After doing so, I tried to run the asset bundle builder like I normally would but it always spams the following error message: > Cannot build asset bundles while imports of assets are in progress. Are you trying to build bundles from within an AssetPostprocessor? UnityEditor.BuildPipeline:BuildAssetBundleExplicitAssetNames(Object[], String[], String, BuildAssetBundleOptions, BuildTarget) I'm not trying to import assets at this point. I can hit the play button and run the game out of the Unity editor just fine, so an asset import is obviously not underway. Restarting Unity doesn't help. Also tried disabling the cache server to make sure that wasn't causing problems. I'm not using an AssetPostProcessor.