It's best that I don't write while I'm sick, especially if I'm running fevers. I'll write posts that don't make sense or have content unrelated to the plot. ~__~ More often than not, I'll get a PM from the other author asking me wtf I just wrote. lol
I do come up with awesome story ideas when I'm ill, though. My most successful group roleplay, in fact, results from a dream I had whilst running a high fever.