First of all, try upgrading svBuilder-Pro to the latest version (v2.1.3).
You can download this version using the SimpleViewer Pro link from your purchase email.
Uninstall svBuilder-Pro v2.1.2 first and then install v2.1.3 using the 'svBuilder-Pro.air' file inside the SimpleViewer Pro download package.
If v2.1.3 still fails, then try the following:
1) Close svBuilder-Pro
2) Delete this folder:
Mac: /Users/YOURUSERNAME/Library/Application Support/Adobe/AIR/svBuilder-Pro
PC (XP): C:\Documents and Settings\Application Data\Adobe\AIR\ELS\svBuilder-Pro
PC (Vista, Win7): C:\Users\YOURUSERNAME\AppData\Roaming\Adobe\AIR\ELS\svBuilder-Pro
3) Restart svBuilder-Pro
Steven Speirs
SimpleViewer Support Team