Hi Peter,
Information:
Irprops.cpl Infrared Port properties
(located in C:\Windows\Driver cache\I386\Driver.cab until you install an
infrared device)
The error message: "Rundll irprops.cpl missing entry Bluetooth
authentication agent" appears when booting a system that had Bluetooth
support installed before being upgraded to Windows XP Professional.
Configure Explorer to show hidden files by opening Local disk C in My
Computer, clicking on Tools, Folder Options, View in and selecting "show
hidden files and folders", then click Apply.
While still In Explorer, find the folder C:\Windows\i386 and open it.
Locate Q323183_WXP_SP2_X86_ENU.EXE and double click on it.
This should install Bluetooth support in the upgraded OS.
If prompted, restart the computer. The error message should no longer
appear.