Well, apply basic settings first, because your problem is vague and hard to identify :
Rendering Engine, use Direct3D HAL
Use a smaller resolution, 800 x 600
Uncheck the full screen mode
Sound, put "No Sound" (you need to scroll up!)
Disable UAC (Start -> Control Panel -> User Accounts and Family Safety -> User Accounts -> Change user Account Control settings -> set it to minimum)
Right-click on SSRO Client.exe -> Properties -> Comptability tab -> near the end, check "Run this program as an administrator"
 
Well you said you did, but... let's make sure, did you run RagnarokPatch.exe?
 
Other than that... well just try these, if it still fails after all (don't forget to reboot after disabling UAC), then... well we'll see then. But you should be able to see SSRO's main client, or at least get an error message that could lead us to somewhere.