some parts of the dvd flicker and glitch like a strobe light

Which parts? Are they parts where you've added text or graphics? What you're describing sounds like a problem with interlacing. Video on most televisions is interlaced, meaning the TV (very rapidly) switches between two alternating sets of lines (called fields) of the video -- half of one frame, half the next frame. This happens fast enough to (for the most part) fool your eye into think you're looking at a complete image.

When there is something in the video content that's very thin horizontally, it may disappear and reappear as the TV alternates between fields. This happens a lot with fonts that use thin horizontal lines (like Times New Roman) and really small type. It also happens with graphics with thin horizontal lines. The solution there is to either use thicker lines or apply a slight vertical blur. The solution for your situation depends on exactly the problem content is (text, image, video) and where that content has been introduced (in DVDA, in Vegas, or even earlier in the process). So, watch the DVD and make a note of what's the screen when this flickiering is worse.

You don't see this when you play the video on your computer because computers don't interlace video. They use progressive, which simply displays the frame instead of alternating lines.

Rob