Invalid parameter message

[PureMoxie]

I'm getting an "invalid parameter" error message for the following two scenarios:

1. Drag an item from the search results/child items pane to the data explorer to create a logical link - the link is actually created and is visible if selecting the item that was the target of the drag, but the data explorer is not immediately updated.

2. Synchronizing a text file with Ctrl + F5 (contents not stored).

I'm using 5.4.0.9