frequent issues using Autocad to connect to SDE

[Anonymous]

We have a few users connecting to a geodatabase (SQL) to work with live data in Autocad Civil3D 2011 (and I've also tried Map3D), and they are able to connect to the SDE fine using the ArcSDE provider, but when they load a .layer file in Autocad for styling the data it frequently either fails to load (yellow exclamation and error), or they can't refresh the layer. I've installed Map3D on one of their computers, hoping that it would "just work" in the product designed for this sort of task, but I had the same difficulty with the .layer files. Sometimes the fix is to remove the layer, disconnect the connection created by the layer file, and load it again - something which just worked for me in Map3D. It seems like the one major hurdle to them being able to work with this data productively is trying to load these .layers and refresh them in Cad.
On the server end, I see "Login failed for user 'sde'" in the sql server log, corresponding with the failed layer loading. The .layer files have hard-coded connection information, in xml format, and I'm not sure if they need to be edited in some way to make them load correctly - or is there a better way to do this whole thing to bypass the Autocad layer flakiness.

Any ideas?

[Gary_Braun]

This may or may not be the problem, but I have seen similar behaviour if Map doesn't know what reference system the data is in or is not able to reproject it, so check your data connection and make sure Coordinate System does not say <unknown>.

[Anonymous]

Thanks, I'll check that next time I'm able to reproduce the problem - users currently report that they have been ok the past couple days. If this streak continues, I'm going to have to come up with something explaining what I did to "fix" it. One thing I did last weekend was move the database files for the sql sde database they are accessing to a local drive, as it had been on an iSCSI networked hard drive that was showing I/O errors in the event log.