Wow, that's an old thread. ;-) What is your WinPE platform (version?) What have you tried so far? Sorry, difficult to edit your reply - a black banner below "Signed in as..." which I can't remove FIrefox 3.6 maybe? Actually it seems that it wasn't a problem with the MBR. To explain: A friend brought me a Win2K machine and asked if I could upgrade it to XP. "No problem", I thought. Hah! As IF! I copied all his hard drive files to another drive. Good backup, eh? Then attempting to upgrade things went pear shaped and locked out his WD drive - still not cured So I copied back the files to a new WD drive. Then I got locked into "cannot find operating system". That's how after much Googling and trying several different methods assuming an MBR problem I arrived here. Last night I wiped the new drive and installed a fresh copy of Win2K and surprise! Surprise - it now works So. It seems that it is/was some incompatibility with partitioning even though boot.ini is/was correct. Never seen this issue before after nearly 20 years with PCs. Maybe it will help someone else. Apologies if I've posted off topic but I've not seen another board thread that talks so much common sense. And many thanks for your reply BTW, I used USB BART PE a couple of weeks ago on a netbook and it went without a hitch.