How to change your PC's name (Windows 7)
1.- Click on "Start"
2.- Click on "Control Panel"
3.- Change the view to "Small icons" or "big icons"
4.- Click on "System"
5.- On "Computer name, domain, and workgroup settings", click on "change settings" (on the right).
6.- On the new window, click on the button "Change"
7.- Change your PC's name to something plain, for example, from H'llo to Hllo.

On that is done, pair your device.

0.- Turn on your n900 bluetooth (if used before with your pc).
1.- On Windows, Click on the "start" button.
2.- Click on "Devices and Printers".
3.- Unpair your n900, by selecting it, right clicking on it, and selecting "Remove device".
4.- Turn off your n900 bluetooth.
5.- Open MaemoBlue on your n900
6.- Click on "Wait for connection".
7.- On your PC, On your notification area, right click on the bluetooth Icon, and select add device, there add your n900 (will be shown as a bluetooth keyboard).
8.- Pair with it. The PC will give you a code that you need to put in the n900, a screen will automatically open on your n900.
9.- Your PC will tell you that it was a success, and is already connected, but your n900 will remain in "Waiting for connection". Just wait a couple of minutes, and it will send you to the menu (Windows 7 is still installing drivers).
10.- Enjoy.

@ VDVsx : I have already reported the bug.

@ nux : What are you pairing your n900 with?