I have a problem with PoEdit (set to parse PHP). Sometimes I'm getting Fatal Error when trying to parse strings with % that are not %s, like "Sword of Chaos adds +100% damage." It happens only sometimes, if I try a few times it will "go through". All %s, like: "Sword of Chaos adds +%s damage." work without problem.

Any idea how to fix it? Is there some setting for it? Is it that PoEdit is crappy and I should use other editor?

If it recognizes % as a code symbol, than you need to find the code for a percent sign.

Similarly, the \ in the C standard lib's print functions is intended to precede an escape code, to to type an actual \, you must type \\. In XML, & is the code for &. And so on.

I don't know exactly what you're using or in what context, but it sounds like that, and also like this is a programming issue.

No, it has nothing to do with programming. It's about PoEdit (translation tool). I wonder how to make it accept "XX%" strings (if I enter these manually into .po file via text editor everything works perfectly).

Does anyone of you did translation (as a writer/translator, not a coder)? What tool you used (for .po files)?

Nope, but it sounds very much like it doesn't want to accept it because it thinks it means something else; ask them.