Fullscreen games don't use full resolution

[TheMitjaX]

So today I came across a problem http://www.tomshardware.co.uk/answers/id-3690447/resolution-randomly-changing-opening-bandicam.html but now the other problem is that whenever I open a game in fullscreen mode it isn't 1600x900 resolution but instead it uses a smaller resolution when I set the game to 1600x900 (seems possible on gta sa) the game crashes and won't load this way. Also on gta games I get random glitches that have never happened before like white screens and then game asking me to insert gta discs.

 

[PuperHacker]

Reinstall the GPU drivers, run antivirus and/or delete Bandicam.