Motsuko, does this happen on both of your computers?
I think the problem isn't from photoshop, if anything, it could be because your computer doesn't have enough RAM, but that's a wild guess... Renders can be huge sometimes, so I guess that could be the problem.. Anyway, how much RAM you got?
If that's not the problem, try deleting your preferences file? Some photoshop problems come from a corrupt preferences file. (C:\Program Files\Adobe\Photoshop\Preferences). When you delete it, it forces PS to recreate it on next opening.
Poke'd, I haven't seen your banner but tutorials are always useful, for beginners and for advanced users, so if you feel like you have the time to do one, go ahead. I'm sure many people will appreciate it ^^