If you can’t open a workflow in SharePoint Designer and it throws the error “Failed to load the workflow” then try the following:
Check Application Data Permissions
1. Check Permissions on the folder:
C:\Documents and Settings\<your user name>\Application Data
2. If you cannot browse to the folder, then change the Owner to your Windows User ID
3. Reopen SharePoint Designer
If that doesn’t work, delete the cached folder found at the following location:
C:\Documents and Settings\<your user name>\Application Data\Microsoft\SharePoint Designer\ProxyAssemblyCache\(12.x.x.xxxx)
