I now have the full answer to the problem.
I purchased a new 8gb sd card and put it in the computer and found that I got the same result as the Sd card from the MD 802 . I then sent question to Microsoft to find out why my computer would not read the cards. They said that Windows XP did not support sd cards above 4gb so the inbuilt card reader in my computer would not read the 8gb card.
The answer is to purchase a stand alone USB card reader which supports SDHC which when plugged into the Windows XP unit enables it to read the higher capacity card. Thanks to Autel support for their help.