This happened to me the first time I enabled it, but after rebooting fixed data once, I've had no issues in the ~ half dozen times I've used it since.Anyone having issues with the wifi hotspot? Every time I try to turn it on, it kills the 3g connection and I can't get it back unless rebooted.
*edit
it crashes when i enable hotspot, give me a stop error. then disables 3g connection.
Maybe try enabling wifi on its own before enabling wifi AP. I got into the habit of doing this under cm7, as it seemed to circumvent the hotspot glitchiness there. Bear in mind, this is probably entirely a placebo solution, but it's at least been working reliably.