Particles and transparent Textures error[solved]

[Kreekakon]

This should probably go without saying, but I'll check anyways: You didn't move any files did you?

Another thing you may want to consider doing is checking the "resources" file, since I heard Steam (If you're using that) had a update which resettled it.

Something else you can try is "redefining" the PSfile you are using in the level editor, by opening the particle selector, and selecting your particle again. This method solved a few vanished objects for me in the past.