Halo and Halo 2 compatability

That is certainly odd. Just to be sure, do you have any other BC games that play properly? When and where was your HDD purchased?

im not sure what you mean by BC game.. none of my originals work on my 360 but just fine in the original console.

 i bought the HDD from some company (or probably person) off of amazon probably about 2 years ago. i bought a 250 before MS sold them alone, assuming it was one off of a special edition elite console. when i got it it had silver stickers over the spec stickers on the bottom (no idea why) and the contents of the drive were all chinese-looking. the underneath sticker says:

Xbox 360 250G HARD DRIVE

MICROSOFT CORPORATION

REDMOND, WA (ZIPCODE) USA

For use with Xbox 360

and it seems to have the proper features such as; an FCC logo, UL listed logo, embossed (in the plastic) Microsoft and a hologram sticker, barcode, one of those crazy black and white pixel scancodes and (what looks like)  serial and item numbers.  the only difference i notice between my drive and others ive seen is it doesnt say the capacity on the top silver metal strip. it just says HDD.

i know its long, but that is the BEST possible description i can give

Sounds like a knocked off one to me.

Yeah, if your console isn't reading any BC (backward-compatible) games, please try the discs on a friend's console, preferably one who got their HDD with their console.