Ok this is going to sound weird but believe me it works.
REMOVE the entries you made and use this EXACTLY.
rompath D:\roms
samplepath D:\samples
inipath D:\;T:\

:;T:.;ini
cfg_directory D:\cfg
nvram_directory D:\nvram
hiscore_directory D:\hi
history_file history.dat
mameinfo_file mameinfo.dat
This will fix it!
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NOW PLEASE get mame off the E:\ drive!!!
Move it to an F:\ partition on a NEW hard drive.
E:\ is needed for other functions and if you fill it, your Xbox will not work.
At the very least have a full backup on hand in case of trouble.