nolimitx

Here are a few things I would recommend trying. This particular error has to do with serialization of a certain file.
 
1. Install Microsoft .NetFramework. Instructions on how to do so can be found on the download page. 
While you are at it, also install the below if you have not already; Microsoft Visual C++ 2010 Service Redistributable Microsoft Visual C++ 2015 Redistributable 2. Ensure your graphics card and drivers are up to date. If they are, simply reinstall them.
NVIDIA AMD Radeon 3. Add / Allow your Grand Theft Auto V folder through your antivirus/firewall. This will vary depending on the antivirus software you use, so please search the internet on how to add an exception to your antivirus. There is the possibility your antivirus blocked it.
4. Right click on SlimDX, found in the main directory, and find "properties", here, go to permissions and allow the permissions Read, Read & Execute, and Access Folders.