AutoCAD Missing Language Pack Drawing File Corruption

I’ve been chasing a drawing corruption problem on behalf of a customer. The problem manifests itself by causing a “Missing Language Pack” dialog to display when the drawing is opened (but only in Windows XP with no language packs installed — my Vista installation apparently has all the language packs installed). Installing the language packs “fixes” the problem, in that the drawing files open without error.

However, the real problem is that some drawing objects were corrupted in memory, and corrupt data was subsequently written to the .dwg file. My customer thinks the corruption might be linked to a virus that they were infected with (and have since eliminated). I have a copy of the virus for testing, but I have not been able to catch it in the act of corrupting an open drawing file. Therefore, I cannot conclusively link the virus with the corruption.

So, I need your help. Have you recently noticed a “Missing Language Pack” dialog appearing in drawing files that have opened fine in the past? Has your virus scanner recently detected an AutoCAD related virus? If you have, please send me an email describing your situation and AutoCAD versions involved. I would like to determine conclusively whether the virus is causing drawing file corruption, and if so, whether the corruption is always in the same location of the drawing file.

[Update: Autodesk has released a technical document with information about the virus. See also Shaan Hurley’s blog post.]