Computer willn't run full screen programmes

So whenever I load up a game (Battlefield, WoW etc) My computer screen will only show me a blank screen the only way for me to exit weas to alt+tab music was still there...Possible problems?

 

Doesn't it seem that way? :confused rolleyes ...lol.

Anyhow, this is likely to be the case of video drivers or DirectX but I have also seen where the DVD-ROM drive I was using was not fast enough (4x), once I installed a (8x) drive it worked fine.
I would start with the games requirements to see if your currect specs, system settings qualify or not. If the same games worked before on this same exact machine with no changes done to machine then I would have to go back and emphasize a software problem, either with one of the two I mentioned above or with the game themselves. Did the games work fine before? Have you installed any updates for the game?

Uninstalling the games and re-installing might help.
After backing up any applicable configuration and saved levels first then uninstalling, reboot the system. Afterwards, remove the game program folders as well if they still exist and then re-install.

Critical question to answer is, did these games every worked on this very machine before? If so, what type of(hw or sw) changes have occured since then?