The Regex of MSBuildParser seems to be applied non-case-insensitive. Your regex
expects the keywords 'warning' and 'error' with lower first letter. However the
C# 2.0 compiler of Visual Studio 2005 produces 'Warning' and 'Error'.

The RegexParser of Hudson Warnings needs to parse regex case insensitive or you
need to change the regex in your MSBuildParser to allow upper-cased first
letters, to support valid VS 2005 outputs.

I have checked your Regex:
(.)((\d).)\s:\s*(warning|error)\s*([^:]):\s(.*) with
http://www.fileformat.info/tool/regex.htm,

using the following input:

[solution] Folder\File.cs(632,11): Warning CS0219: Die Variable result ist
zugewiesen, ihr Wert wird aber nie verwendet.