DVD Audio is Choppy

[Xestrix]

VLC: 0.8.6c
OS: WinXP Pro SP2
CPU: 2.8 (dual-core)
Mem: 2gb DDR2
Drive: SHM-165H6S (LITE-ON)

So, on my girlfriend's computer (specs above), while playing DVDs, the video will run smoothly with no issues, but the DVD's audio will stutter constantly. The only time this problem is encountered is while playing DVDs. Any other format plays both video and audio fine.

Also, her secondary DVD-ROM (DROM6216 [Phillips]) drive plays DVDs fine. Anyone have any ideas?

EDIT: After updating the drives firmware, the stuttering is reduced, but still apparent. Where before I would have described the stuttering at about 90%, now its at about 15%. But I'd still like to fix that as well. Also, in other programs (WinDVD), the stuttering is still a non-issue.