Basecamp 4.6.2 vs Astro 320 4.40

I have Basecamp 4.6.2 installed on my laptop. I am running Windows 7 Ultimate SP1 (32bit version). My antivirus and firewall are turned off. I have installed the Garmin USB drivers. I have a Garmin Astro 320 (Software version 4.40), with the Garmin OEM SD card with the 1:24k Mid Atlantic topo maps.
I purchased the download version of Garmin's 1:24k topo maps for the South East US region from Garmin's website. I am trying to download this new map region.

Basecamp will not read the maps or track data from the OEM SD card in the Astro. However, Basecamp will show the Astro in the [Device List] "Astro ID xxxx/ Basecamp" on the left menu area. The Astro does not appear in the [Send to Device] or [Receive from Device]. The OEM maps on the OEM SD card are not listed in the [Manage Map Products] menu either. Basecamp will read and display the maps when I insert the OEM SD card into my laptop's card reader. The maps are also displayed in the [Manage Map Products] menu.

When I try to download the new topo maps (1:24k South East US) from Garmin's website, I get:
Computer ready for download,
Device found: Astro 320 Software Version 4.40 - S/N xxxxxxx (undefined MB available)

When I click install, I get the following errors:
"Unable to get property 'firstChild' of undefined or null reference
---or---
Plugin error: source: IOU_USBLINKIMPL.CPP, line: 49

When I try to purchase new maps thru Basecamp,

This happens regardless of which card is in the Astro. I have tried the Garmin OEM SD card (4GB), 16GB card and a 32GD card. All cards were formatted as FAT32, 4096 byte allocation size.

Garmin products nor their support are user friendly. I am ready to go back to a paper map & compass. At least it's reliable and dependable.
Can anyone offer any assistance?
Garmin tech support?

D