I have saved the install files (including the CHM file) on my G: drive. The file I am attempting to open is the "K2 [blackpearl] Getting Started.chm" file (in BP Service Pack 1).

(i.e. "G:UtilitiesK2BlackPearl_Sp1SP1K2 [blackpearl] with Service Pack 1 - Build 014")

I am running Windows XP Professional. Past recommendations was to copy the file onto a Windows 2003 server VPC and open it ther (not a very convenient option). 

I suspected it was due to any/all of the following:

• 
  
• Long path name string
  
• Special characters in the path name
  
• Non-standard drive
  
• missing HH.exe (Windows Help application)
  
• Not sufficient Permissions
  
• Alternate/unsupported drive format

My troubleshooting has included:

• 
  
• I am a local admin on the machine.
  
• Attempt to load other CHM files works.
  
• All drives are the NTFS format (no differences).
  
• Copied the file to root folders and a subfolder on my C:, , J: drives. CHM Loaded fine in each test.
  
• Copied the CHM file onto my (Windows XP) Desktop. It loaded fine.
  
• Copied the file into the various parent folders on the G: drive (all worked).
  
• Attempting to opening it again from the original 'problem' folder worked (?!)

Barring further research, I can only guess that the file was eventually cached (Windows took a while to index the new G: drive contents (an external USB drive, as was the J: drive). Now that the CHM file is recognized, it loads the menu and contents every time without an issue.

Recommendation: Copy the CHM file to the Windows Desktop and open it. It should open. If not, try another common Windows folder ('My documents') and attempt to load it.

Cheers.

look at the second pic via this link: http://blogs.msdn.com/robcaron/archive/2005/06/23/431976.aspx and you'll see the unblock icon.

It occurs on XP if you have a standard security update installed.  Happens always with Vista.

I don't have that "unblock" option, It is my first time see that picture. Anyway, You may also visited the following link,

http://www.microsoft.com/downloads/details.aspx?FamilyID=a637eff6-8224-4b19-a6a4-3e33fa13d230&displaylang=en

It is a link to download Admin Sharepoint 2.0 chm, in the bottom area,

Known Issue: Text in file not appearing as expected

If you installed Microsoft Windows security updates MS05-026 or MS05-001, the text in this file might not appear as expected. The messages "Action canceled" or "The page cannot be displayed" might appear.

To open this file to view the text:

1. 
   
2. Click Download.
   
3. In the File Download dialog box, click Save.
   
4. Use the Save As dialog box to save the file to your computer.
   
5. Find the file on your computer and double-click it.
   
6. In the Open File dialog box, clear the Always ask before opening this file check box, and then click Open.

So you may also try to clear the "Always ask" checkbox too.

I'm not sure if this explains why it fails to load from one folder location, but does from another.

I appreciate everyone's contributions/insights...all great stuff!