I've got a couple of unzipped sets that are failing to rebuild or scan with ClrMamePro:

Tales Of The Arabian Nights - Pinball Ken (Williams) (1996)
2 in 1 - Whizball (Peo Manufacturing) (1930) & Midget Bagatelle (xxxx) (1940).zip

using Yori Yoshizuki's VP dat and Claudio's VPinMame dat respectively.

Both of these folders have very long filenames for the included files, which looks to be the root of the problem. I've changed my rom drive from FAT32 to NTFS, but it makes no difference. Shortening the filenames in the dats works (at least for Arabian Nights), but it's a lot of mucking about when new dats are released. Anyone know how to deal with this without editing the dats? Or have I misdiagnosed the problem?