Ok, i've noticed a bunch of replies regarding this issue...and i know there are already about 20 threads with multiple answers to the infamous question, "How do i run Deus Ex 2 from my HD?" and "Deus Ex 2 jumps back to the dash after trying to load!" but i simply didn't feel like reply to each topic so here is what i did:
1) Use the latest versin of DVD2XBOX to copy the game to your HD
2) Simply use DVD2XBOX to patch the other 2 xbe's in the Deus Ex game directory. These files are Default.xbe, DX2Realease.xbe and xbErrorReport.xbe. Since DVD2XBOX automatically patches Default.xbe, there is no need to patch this again. Simly browse your files and folder via DVD2XBOX (Press 'B' at the selection screen, then highlight one the two xbe's mentioned above, hold 'Left Trigger' and select "Patch Media Check 1/2". Do this for both xbe's!!!
Forget about all the other so called "fixes" you have read about. I did not modify any INI files are anything of that nature. Here are my xbox specs incase you feel that may have something to do with this error:
TSOP Flash with Multi-Bios Boot via Mounted Switch (For Xbox Live)
Bios 1) MS OEM 4034 Bios
Bios 2) X2 4973 (xbox version 1.0 specific) Bios
I hope this post helps you, as i found it extremely frustrating trying to fix this stupid problem.