Hi there, I have a T61p machine with Vista Ultimate, SP1. I have all the latest patches from Lenovo.
I have a docking station that I use at my desk. When the machine is docked I used a Microsoft Intellimouse Explorer for Bluetooth and Keyboard Elite for Bluetooth.
Ever since I purchaced this machine (about 3 months ago, with Vista Ultimate) I have been having the same issue. If I have not used the keyboard for sometime (say greater than 5 minutes) the first time I click any key on the keyboard, the machine partially hangs. It will continue to play video or do other non interactive tasks, but for the next 45 seconds to 1 minute, the machine will not accept input from the keyboard, and it won't accept input from the mouse.
I previously used the same Bluetooth mouse and keyboard with a Dell laptop and had no such issues (in fact, I still own that laptop, and it still has no issues with this keyboard and mouse)