Okay, everyone back up. This is incredibly stupid.
Theqmayn, you should download
SLADE, and spend a little time experimenting with it to figure out how it works. XWE is beyond ancient and no longer updated. This means it contains tons of known bugs and other issues that will cause you problems, like the corruption issue you're having. While SLADE is slightly more complicated, it's way more stable and is still actively maintained. It might annoy you at first to learn a new interface, but you'll be far better off once you figure out how it works.
To everyone else in this thread, the goal of this forum is to help people edit SRB2, and to that end we should not only provide current information, but enough information that it actually answers the question. Saying "use SLADE" or "don't use XWE" doesn't provide any helpful information to anyone. You've gotta tell people
why they should use SLADE over XWE.
To the XWE lobby, I'd like to point out that XWE was last significantly updated almost a decade ago. While many of you have been using XWE for an eternity and therefore know its quirks inside and out, that doesn't mean newbies to editing should be using it. We don't provide support for Wintex and WadAuthor anymore, so why should we continue to do that for XWE? I'd like to remind you that while I was using WadAuthor for long beyond the time when I should have been, I recommended everyone use Doom Builder once it was stable. I knew all of WadAuthor's bugs by heart, but anyone new to SRB2 level editing would have to learn how to edit stages AND handle WadAuthor's ancient bugs at the same time. At this point it's time to treat XWE the same way: a historical relic you can technically use if you've been using it for years, but something newbies should stay far, far away from.