Any thoughts as to why?

well the way i do it is when my download is done youst drag the song into your library from itunes if that can't work save it then open it on itunes if you tried this well i don't know what may be wrong and also check the version of limewire i am not sure if that can affect you

i have the same problem

The greatest thing about LimeWire is that it automatically sends the file to iTunes when it works. Maybe I'm lucky, or perhaps I'm just blessed by Steve Jobs, but so far I'm getting about an 89% successful import ratio. And every work-around that I've tried on the Mac has worked out sufficiently, though I'm not happy with the ever-intrusive RIAA, or their Chicago-style 'enforcement' schemes, so cleverly concealed.

Lord of the Rings says it's as basic as checking the option [YES] under LW's preferences.
_ _ _
Try this: Open I Tunes, and it's prefs panel. Insert a CD, and set the importing choices to something logical. Slower is better, High/Medium resolution MP3 by default, "AUTO-IMPORT" on inserting a CD. <<this may be critical.

Also, what happens within your Windows Audio control panel options? Is it even possible to set MP3 as your 'default'? [I'm doing mac, on mac, on mac,--so whadda I know?]

{"God, please reassure me there will be no more Windows OS issues in heaven."}