Joemarcano

You are fairly vague with what you are doing exactly, though I can say what I believe has been the case for the last two people that asked relatively similar questions.
 
Visit Windows Settings -> Privacy & Security -> Virus & Protection -> Protection History and see if Windows has recently blocked/flagged any files recently. Depending on what the file was that was blocked, you can do one of 3 things;
Add your Grand Theft Auto V main directory (GTAV folder) to your antivirus exclusions Windows Settings -> Privacy & Security -> Virus & Threat Protection -> Manage Settings -> Add or remove exclusions -> (Add your Grand Theft Auto V folder here) -> Save -> Relaunch RPH/LSPDFR Check your recently blocked files in your protection history. Windows Settings -> Privacy & Security -> Virus & Protection -> Protection History -> Allow the file it flags (This should be something along the lines of "temp" You can also try to delete the "temp" folder, though that has not seemingly worked for most people, or so I am told. Temporarily disable your anti-virus, run RPH, and enable it when the game launches. Do not fully disable your antivirus otherwise and ensure it is re-enabled when the game begins to load.