This is not my usual kind of post, but still a technical issue I recently delt with. iTunes kept notifying me of a new update (ver. 1.2.3) for my iPod. Whenever I'd try and download and/or update it, iTunes would crash with an error in a DLL, RICHED20.DLL.
After a search of my system (Vista), I found that I had multiple versions of this dll on my system, one in windowssystem32, one in the MS Office install directory and then a couple install and dll cache diretories. As it turns out, the one in my system32 directory was the one causing problems. I copied the one from my office directory into the iTunes program folder and like magic my iPod could update again.