Oblivion help

I just recently played oblivion and finished the game. I wanted to try the expansion packs so i got knights of the nine and shivering isle. when i try to install either one, i receive these error codes. any help is appreciated.

Gateway FX laptop
vista home premium 64 bit
intel core 2 duo 2.26 2.27
4g ram
1g video

Error Code: -5004 : 0x80070002
Error Information:
>SetupDLL\SetupDLL.cpp (3085)
PAPP:Oblivion - Knights of the Nine
PVENDOR:Bethesda Softworks (##ID_STRING1##)
PGUID:14C87AA7-08E6-419F-A165-998EBE5023D7
$11.0.0.28844PAK
@Windows Service Pack 2 (6002) BT_OTHER 55884.23

Error Code: -5004 : 0x80070002
Error Information:
>SetupDLL\SetupDLL.cpp (3085)
PAPP:Oblivion - Shivering Isles
PVENDOR:Bethesda Softworks (##ID_STRING1##)
PGUID:CA4F701A-FB1B-47AC-9A13-56274614A575
$11.0.0.28844
@Windows Service Pack 2 (6002) BT_OTHER 55884.23

 

First things first: Update everything. Vista, drivers, DirectX, and any other you can think of. After that, try reinstalling but this time, run them "As Administrator" (right-click and pick that option).