Appbase being set to nothing at runtime

I have a difficult to reproduce error on about three user installs out of 20. This is a .net Windows application, 2005 in VB.Net running on XP. After opening up a window, we get an error:

Could not load file or assembly 'Infragistics2.Win.UltraWinChart.v8.2,
 Version=8.2.20082.1000, Culture=neutral, PublicKeyToken=7dd5c3163f2cd0cb' or one of its
dependencies. Element not found. (Exception from HRESULT: 0x80070490) *****ClearTrac *****
   at ClearTrac.ucNav.InitializeComponent()
   at ClearTrac.ucNav..ctor()
   at ClearTrac.frmPortfolio.InitializeComponent() ...

This happens also for the ReportViewer dll and a couple other infragistics dll's. I turned on Bind Logging, and the first binds are ok, but when I get the error, the Appbase has been set to blank:

*** Assembly Binder Log Entry  (2/20/2009 @ 3:41:10 PM) ***

The operation failed.
Bind result: hr = 0x80070490. Element not found.

Assembly manager loaded from:  c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\mscorwks.dll
Running under executable  C:\Documents and Settings\rdelaney\Local Settings\Apps\2.0\ZZ09GJK6.2VY\GPRTP6CM.GOX\clea..tion_8055aae51715540e_0001.0004_0a540274bbdc609c\ClearTrac.exe
--- A detailed error log follows.

=== Pre-bind state information ===
LOG: User = CAM\rdelaney
LOG: DisplayName = Microsoft.ReportViewer.WinForms, Version=8.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a
 (Fully-specified)
LOG: Appbase = 
LOG: Initial PrivatePath = NULL
LOG: Dynamic Base = NULL
LOG: Cache Base = NULL
LOG: AppName = ClearTrac.exe`
Calling assembly : ClearTrac, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null.
===
LOG: This bind starts in default load context.
LOG: Using application configuration file: C:\Documents and Settings\rdelaney\Local Settings\Apps\2.0\ZZ09GJK6.2VY\GPRTP6CM.GOX\clea..tion_8055aae51715540e_0001.0004_0a540274bbdc609c\ClearTrac.exe.config
LOG: Using machine configuration file from c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\config\machine.config.
ERR: Unrecoverable error occurred during pre-download check (hr = 0x80070490).

Any ideas?

From stackoverflow

• You should check that on problematic computers the Microsoft.ReportViewer.WinForms is either in GAC or in application directory.

  If it's not, you should install Microsoft Report Viewer redistributable on problematiuc computers.

  http://www.microsoft.com/downloads/details.aspx?FamilyID=cc96c246-61e5-4d9e-bb5f-416d75a1b9ef&displaylang=en

• We found this error only happens under the .net Framework with SP1 or SP2 installed. With the bare .net framework 2.0 installed, it does not happen.