It's not you, and it's not a "problem"-it's a feature.
According to the specs, the 10D AF is good down to EV 0.5, but that's compared to other Canon models with AF sensitivity of EV 0. I don't know how to quantify that one-half EV, but I noticed a substantial difference between the low-light AF performance of my 10D and the A2 it replaced. I do a lot of nightclub photography, frequently in almost total darkness, so it was pretty easy to see [so to speak] the difference between the two. I chalked it up to the A2's automatic near-IR AF-assist l&. The 10D has an AF-assist l& too, but it's basically just the built-in flash firing a short burst, only in certain shooting Modes, though.
The solution is to use a Speedlite with a built-in near-IR l& which can then be used for AF-assist. Canon must have known this would be an issue for some people, because they included a Custom Function to turn off just the flash of an external Speedlite, essentially making it a big IR AF-assist l&.
It may be a drag, but consider it just another good reason to add a EX Speedlite to your kit.
