Had the same problem coming at me randomly at the time my mods were working. All I did was installing GTA to another location, aswell SAMP. Remember to delete the old GTA folders before you pull a stunt too and any old files related to it.
As for IMG tool I suggest you use Sparks. IMG tool is like using your thumb instead of a piece of paper cleaning your ass after being at the toilet, I'm serious too.
Let me know if it's working or not so I know if I gotta figure another way out.