I would like to know if you have tested the behavior of your system with the following drivers.
1. OEM drivers: Product Support | Dell US (make sure you select the correct OS and version.
2. Default driver from Windows 7* (uninstall the current drivers for display adapter,Intel® HD Graphics, and let the system reboot.)
3. Intel® generic drivers: Drivers & Software (also make sure you select the correct OS and version 32/64-bit)
If found this that could also be the issue you are encountering with, this is related to FilterKeys.
I look forward to your outcome with this.