Sounds like you are using the PAL version of the game. That version has emulator problems like you described.
Use the "Star Wars Arcade (32X) (U) [!].32x" version of the rom.
[Checksums of the USA version before zipped = CRC-32: 2f16b44a, MD5: ae3a42c6297ef25c6018a209fda0194e]