Maybe you can try a different method:

1- make a backup of you rom collection (just to be on the safe side...)
2- move all your roms sets into a temp directory, leaving the mame/roms directory empty
3- use the rebuilder function of clrmame, setting as a source the temp directory where you moved all your roms sets, and as destination your mame/roms directory.
4- in the merge option check "split sets"
5- in the options check "zip files", "remove sourcefile".
6- hit the rebuilt button and wait...
7- when rebuilt has finished, make a scan; whatever you are missing, you need to redownload.
8- you can now safely delete your backup and your temp folders.


ciao
f205v