Topic: "vla-RefreshPlotDeviceInfo" creates new network-mapping

[Peter2]

For AutoCAD 2011, Win 7 x64
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For years I have a code which sets a CTB to a current drawing. It starts with

Code - Auto/Visual Lisp: [Select]

1. (setq ad (vla-get-activedocument (vlax-get-acad-object)))
2. (vla-RefreshPlotDeviceInfo (vla-get-activelayout ad))
3.  

The client has two departments,
- the main department uses drive "q:\" to map to a network-drive with drawings and system-files
- the smaller department uses drive "q:\" (redirected to a local drive) for system-data and "r:\" to map to the data-drive of the main department

The code runs for years unmodified and without problems; since 3 weeks the command

Code - Auto/Visual Lisp: [Select]

1. (vla-RefreshPlotDeviceInfo (vla-get-activelayout ad))

invokes a new mapped drive to the data-drive. It happens only if called from the smaller department, the main department has no problems.
It is a kind of copy of the "r:\" mapping, it begins with "z:\", the following usage of the command takes "y:\" and uses all unused letters up to "h:\". The user says that "nothing was done, nothing was changed".

Who can help?