AutoCAD LT :: Opening DWG Read Only

We have a problem with using our AutoCAD LT 2012 on our the network:

If a folder on the network is for the designer read-only, AutoCAD file open and reports the error "drawing file is not valid". Designers who have write-access to this folder open files with the same version AutoCAD (LT 2012) without a problem. If I add write-access right to users to this folders, he open it fine.

The problem is only with network folders (sharing Win2008 server); if it is a local folder with read-only access, AutoCAD will recognize it and offer opening for reading only. This version (LT 2012 SP2) has apparently some problem with access to network folders with read-only rights.

If the file is opened via the "Open read-only" from the pull-down menu in the Open AutoCAD dialogue, it works well. This approach is however very inconvenient - designer finds a link to a file in our information system, he wants to open the file, but get the above error.

Copy the file to local disk isnt usually possible, because of using XREFs files, which he also need to load.

The problem is possibly in an attempt to create a DWL file. We didn't use the function WhoHas, so that a possible solution would be to disable the creation of these DWL files. But this option in ACad LT 2012 isnt possible.Is is solution to migrate to new AutoCAD LT 2014?