This generally happens for two reasons:
- You've inserted code into the stacks and the code has a syntax error.
Solution: remove the bad code or fix the syntax errors.
- Some styled text, copied from another app and pasted into RapidWeaver.
RapidWeaver can only render certain web-compatible styles. The RapidWeaver styled text engine can get confused when you paste content into it from other places. Although this problem manifests in complex layouts more, so Stacks is very affected by it, all RapidWeaver page styles suffer from the same limitation since the RapidWeaver rendering engine is one of the fundamental building blocks inside RapidWeaver. In other words, if you paste the same content into a blog page, it will mangle your blog too.
Solution: The solution is pretty straightforward. Don't paste styled content in from other apps. If you do need content from elsewhere, use the menu option in the File menu: Paste as Plain Text. This will strip the incompatible styles from the text before it's pasted. Then use the the RW/Stacks style tools to style the content.