Unhelpful exception information in GetFileHash

[wixbot]

I have a rather large wix file and light is throwing an
error which doesn’t pinpoint me to where the error might
be.

light.exe : fatal error LGHT0000: Input string was not in
a correct format.

Stack Trace:
at System.Text.StringBuilder.FormatError()
at System.Text.StringBuilder.AppendFormat
(IFormatProvider provider, String format, Object[] args)

at System.String.Format(IFormatProvider provider,

String format, Object[] args)
at System.String.Format(String format, Object arg0,
Object arg1)
at
Microsoft.Tools.WindowsInstallerXml.Msi.MsiBase.GetFileH
ash(String filePath, Int32 options, In
t32[]& hash)
at
Microsoft.Tools.WindowsInstallerXml.Linker.UpdateFileInfo
rmation(Output output)
at
Microsoft.Tools.WindowsInstallerXml.Tools.LightMain..ctor
(String[] args)
at
Microsoft.Tools.WindowsInstallerXml.Tools.Light.Main
(String[] args)

Originally opened by teyc from http://sourceforge.net/p/wix/bugs/38/

[wixbot]

Suspect problem was caused by a file with a name
called "#readme.txt#", and using the FileGroup tag.