This is one of the wackiest and weirdest problems I have ever encountered. My keyboard was working absolutely fine untill yesterday on Ubuntu 13.04. However, when I boot to Ubuntu today, I suddenly find that all the keys work, but I have to press and keep on holding them for about a second for them to work.
This behavior is true for all the keys except for Num Lock, Caps Lock and Scroll Lock keys, the indicator for them on my keyboard lights up as soon as I press those keys.
The keyboard works fine at the login screen where I put my password.
The keyboard also works normally if I use the Guest session instead of my normal user account.
I have not done any key-remappings and using the standard English (US) keyboard layout.
I have fiddled around with the settings for Keyboard in System Settings, but to no avail.
I have Windows 7 as dual-boot and the keyboard works perfectly well on it.
Why am I facing such a behavior and how to normalize this?
PS: Using Logitech Classic Keyboard K100 (USB Model).