mejutty,
I experienced the same issue, usually once the drives start to fill up. I posted same issue on other forum, which someone posted some recommendations on how to potentially fix, see posts here:
http://lime-technology.com/forum/index.php?topic=4500.msg85277#msg85277
Maybe they will work for you? Didnt for me, but given its only really every now and then, and doesnt appear to create a hole in my parity i keep going as normal. It usually only occurs the first time i write to that particular drive as well ie if i have shares spanning multiple drives, first write to one drive may fail then work, then next write to another drive will fail then work. Once it fails once, every subsequent write to that drive works fine.
If you figure out a solution i would be keen to hear.