I believe clifface is correct. I modded my xbox and in copying the orginals C: and E: directorys I missed a folder essential to the dash becuase my ftp program had a glitch in it's directory listings. therefor I could not access the ms dash. I then discovered my mistake last night with an updated version of the ftp program. I then copied this folder to my modded hd and launched xboxdash.xbe to make sure it functioned and so it did at this point I believe the updated xboxdash.xbe detected my mod as it was in mode 2. I then proceeded to the xboxlive dash through the ms dash and got the now famous XBL live could not be found. this explains it as the updated xboxdash.xbe must record the fact it detected a mod chip and then when you next launch xboxlive dash and the connectivity test is make it to the XBL live step it sends the mod information to XBL. So even if you have made it right with a new serial/mac be careful and don't access the ms dash from anyother program, disable the mod with a switch or use mode 3 on your matrix.