Windows 8.1 not opening applications/exe files?

I have recently purchased this new toshiba windows 8.1 64-bit laptop and having a problem with it. At first it would allow me to install and run downloaded programs from the internet. Now it comes up with the same usual warning about the program making changes to my computer. What i would usually do is allow it to run and it will. Now when i choose to run a new program i downloaded it comes up with the same message and i press run like the usual. "Do you want the fallowing program from an unknown publisher to make changes to this computer?" But after i push yes it just does not do anything at all. I also tried opening it as administrator bit still nothing. I tried looking thrugh task manager to see if it was just a wizard not responding or anything like that but the program i downloaded does not even show up at all when i push run. I tried installing different programs to see if it was just the certain VLC medi player tat was not working but other downloaded program would not start either. Oddly enough the ones i have already installed and used before are working and running fine. I would ery much appreciate it if someone can help me figure out what is going on here.

I greatly apreciate any feedback or help with this problem.