Grab it direct and find out, you can't install it if you already have it:
http://usa.autodesk.com/adsk/servlet/ps/dl/item?siteID=123112&id=15073321&linkID=9240818
code 1618 is a system error, outside of AutoCAD, something to do with your
network or access etc.
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Dean Saadallah
http://LTisACAD.blogspot.com
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