"Failed to load the workflow" error popup when try to open workflow in SharePoint Designer

When you open SharePoint Designer 2007 to create a new workflow, you get this error “Failed to load the workflow”

Solution One:
- Go to C:\Documents and Settings\<your user name>\Application Data\Microsoft\SharePoint Designer\ProxyAssemblyCache\(12.x.x.xxxx)
or
C:\users\<your user name>\Application Data\Microsoft\SharePoint Designer\ProxyAssemblyCache\(12.x.x.xxxx)
and delete 12.x.x.xxxx folder.
- Open SharePoint Designer again and it should work this time.

If it is still not working for you then try

Solution Two:
- Change trust level in the .NET 2.0 Configuration (the MMC snap-in, found in Administrative Tools).
- Go to .NET Framework 2.0 Configuration > Runtime Security Policy.
- Choose “Adjust Zone Security” and change Local Intranet to “Full Trust”
It should now work at this point, if not
Go to Intranet options, pushed the slider up to full trust.
Someone might have posted about that but it’s good if this post can help few.