My guess is that the laptop is seeing the dongle as a flash drive rather than a modem. Try this and see if it works.
Go to start menu then 'my computer' and see if there's an icon in there called 'BT CM' normally under 'removeable drives'. If it's there, right click it and go to 'explore' Then locate a file called ejectCD.exe and double click it. Wait for a minute and see if this allows connection manager to install.
If none of that works, have a look in device manager and see if it's detecting the dongle under 'modems' or 'hard drives'. See if there's an internal 56k modem and disable that if there is one.