More fun and pain with Visual Studio.  Visual Studio 2005. 
About two months ago, I started an assignment.  In my role, I cannot install or configure development software.  Trust me this has given me plenty of heartburn.   No IIS is involved here, just File Sharing. 
That being said, when I first started I had a problem with my debugger not working.  The debugger just stopped.  I was able to get it working.  Now the problem has returned and I am pulling every last hair on my head.  
Almost none of my symbols loads. It can't find the PDB files. 
In Debugger options, I checked the Symbol section. 
My symbol file location entry is completely blank. ?  I don't know why.  I did not touch this prior to the problem occurring. 
I have cleared the Temporary ASP.NET folders. 
Example: 
Here is my Module Output 
CppCodeProvider.dll C:\Windows\assembly\GAC_MSIL\CppCodeProvider\8.0.0.0__b03f5f7f11d50a3a\CppCodeProvider.dll  No  No  Cannot find or open the PDB file.       17  8.0.50727.762   12/2/2006 4:23 AM   6A510000-6A52C000   [1844] WebDev.WebServer.EXE: Managed    
WebDev.WebHost.dll  C:\Windows\assembly\GAC_32\WebDev.WebHost\8.0.0.0__b03f5f7f11d50a3a\WebDev.WebHost.dll  No  No  Cannot find or open the PDB file.       3   8.0.50727.42    9/23/2005 4:20 AM   6D040000-6D050000   [1844] WebDev.WebServer.EXE: Managed    
So I enabled the SHFUSION.dll in my versio of the the Framework I am using...
In my GAC, I can see this version of WebDev.WebHost.dll for example: 
ProcessArchitecture(x86)
Public key token matches: 
b03f5f7f11d50a3a
8.0.50727.42
I then see some custom dlls. 
I should note, I created a new project.  Recreated my files manually by importing them.  The debugger worked 5 times and died. 
I'm at a loss of what to do next? 
The obvious has been checked:  The project is set to Debug
Configuration Manager Configuration Debug  Platform .NET  Build : checked. 
Web.Config: 
    
I have attempted to manually attach to the Webdev process from the Debug window and that doesn't work. 
I have googled this and this problem seems to occur quite a bit.