Did you re-install the driver for the keyboard? Does you computer have the latest Windows updates?
Check Device Manager by right clicking on My Computer and selecting 'Manage'. In the window that opens, choose 'Device Manager on the left hand side. Press the '+' next to Keyboard and see if there is an update for the driver by right clicking on it and choosing 'Update Driver'. Let windows access the internet and locate it for you. If that is not successful, go to the keyboard manufactures website and download a driver for it and install it.
Check Device Manager by right clicking on My Computer and selecting 'Manage'. In the window that opens, choose 'Device Manager on the left hand side. Press the '+' next to Keyboard and see if there is an update for the driver by right clicking on it and choosing 'Update Driver'. Let windows access the internet and locate it for you. If that is not successful, go to the keyboard manufactures website and download a driver for it and install it.