Intermittant problem with new bluetooth connection

I have a Dell studio 15 with Windows 7 and Bluetooth. I am trying to install Manhattan 2800 Bluetooth bookshelf speakers. They sometimes play but disconnect intermittently. When Bluetooth disconnects I have to completely shut down and start over. (I haven't been able to fix it with just Restart.)

Here is a clue:
In "devices and Printers" it shows the laptop as a device:
Studio 15 [properties]

Selecting: [Bluetooth L2CAP Interface] -- properties/General
"Device status
Windows cannot verify the digital signature for the drivers required for this device. A recent hardware or software change might have installed a file that is signed incorrectly or damaged, or that might be malicious software from an unknown source. (Code 52)"

Selecting: [Bluetooth Hands free audio] -- properties
Driver= Broadcom Corp, 7/1/2009,6.2.0.9500
Digital Signer: Microsoft Windows Hardware compatibility Publisher.

The speaker documentation indicates Bluetooth v1.2, class 2 and A2DP protocol support

The Bluetooth icon on the bar at the bottom of the desktop disappears when the connection breaks while looking at properties.

This might be related -- I also have a Kensington Bluetooth trackball mouse that has intermittent problems with connecting at start-up. When the mouse doesn't work at start-up, I can usually make it work by removing its batteries and putting them back.

Advice will be appreciated,
Stan Hilliard

Thanks,

How will a USB based Bluetooth adapter interact with my current internal Bluetooth?

Do I disable the current internal setup to use a USB based Bluetooth adapter?

Also, can internal Bluetooth devices be updated or replaced?