@Mike: It showed up mysteriously one night. I've searched the csproj file, but there's no mention of a CSC97.tmp (I also checked the solution file, but I had no luck there either). In case it helps, I've posted the contents of the csproj file on pastebin.
@Derek: No problem. Here's the compiler output.
------ Build started: Project: Infralution.Licensing, Configuration: Debug Any CPU ------
Infralution.Licensing -> C:\Documents and Settings\Dan\Desktop\Rowdy Pixel\Apps\CleanerMenu\Infralution.Licensing\bin\Debug\Infralution.Licensing.dll
------ Build started: Project: CleanerMenu, Configuration: Debug Any CPU ------
C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Csc.exe /noconfig /nowarn:1701,1702 /errorreport:prompt /warn:4 /define:DEBUG;TRACE /main:CleanerMenu.Program /reference:"C:\Documents and Settings\Dan\Desktop\Rowdy Pixel\Apps\CleanerMenu\Infralution.Licensing\bin\Debug\Infralution.Licensing.dll" /reference:..\NotificationBar.dll /reference:..\PSTaskDialog.dll /reference:C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\System.Data.dll /reference:C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\System.dll /reference:C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\System.Drawing.dll /reference:C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\System.Windows.Forms.dll /reference:C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\System.Xml.dll /reference:obj\Debug\Interop.IWshRuntimeLibrary.dll /debug+ /debug:full /optimize- /out:obj\Debug\CleanerMenu.exe /resource:obj\Debug\CleanerMenu.Form1.resources /resource:obj\Debug\CleanerMenu.frmAbout.resources /resource:obj\Debug\CleanerMenu.ModalProgressWindow.resources /resource:obj\Debug\CleanerMenu.Properties.Resources.resources /resource:obj\Debug\CleanerMenu.ShortcutPropertiesViewer.resources /resource:obj\Debug\CleanerMenu.LocalizedStrings.resources /resource:obj\Debug\CleanerMenu.UpdatedLicenseForm.resources /target:winexe /win32icon:CleanerMenu.ico ErrorHandler.cs Form1.cs Form1.Designer.cs frmAbout.cs frmAbout.Designer.cs Licensing.cs ModalProgressWindow.cs ModalProgressWindow.Designer.cs Program.cs Properties\AssemblyInfo.cs Properties\Resources.Designer.cs Properties\Settings.Designer.cs Scanner.cs ShortcutPropertiesViewer.cs ShortcutPropertiesViewer.Designer.cs LocalizedStrings.Designer.cs UpdatedLicenseForm.cs UpdatedLicenseForm.Designer.cs
error CS1583: 'C:\Documents and Settings\Dan\Desktop\Rowdy Pixel\Apps\CleanerMenu\CleanerMenu\obj\Debug\CSC97.tmp' is not a valid Win32 resource file
Compile complete -- 1 errors, 0 warnings
------ Skipped Build: Project: CleanerMenu Installer, Configuration: Debug ------
Project not selected to build for this solution configuration
========== Build: 1 succeeded or up-to-date, 1 failed, 1 skipped ==========
I have also uploaded the icon I am using. You can view it here.