Have you ever had to deal with this with your customers?

Check this out: 

http://www.cadnection.com/

The high level features of CADnection are as follows:

·         Check-in/out to SharePoint libraries from AutoCAD, including Xrefs/blocks.

·         Launch AutoCAD and check-out a file directly from a SharePoint library.

·         Search for file names and contained meta-data.

·         Associate workflow/events based on file changes.

Siatro