1) Current under or over voltages can both cause this behavior. Stick a meter in the outlet and see what you get, you should be reading about 118V. Undervoltaging causes increased amperage, which causes heat that can burn out electronics over time. Overvoltaging can damage the components directly. This really applies to micro-electronics only, as the heating elements of things like toasters are immune to these effects, but the timer bits are still relatively sensitive.

2) I agree on the wet or young wood. New wood (wet on the inside still) burns with much more smoke than very dry wood. The downside of using very dry wood is that it burns MUCH quicker. I have some wood I've been burning recently that I cut pre-Katrina. It's been sitting in my garage for almost 2 years. Burns VERY hot and VERY fast. So fast that 4-5 normal sized logs are completely gone in 10 minutes. On the upside, they require no kindling other than used newspaper. Downside is I have to keep adding logs every 10 minutes to keep a fire going.

Increasing the chimney length will do 2 things. First, it will get the smoke above you, where it isn't a nuisance. Second, it will cause the fire to burn faster and therefore hotter. Closing off some of the entrance to the chiminea will also produce a blast-oven effect, forcing more air on a localized part of the fire, making it burn quicker.

I once blew the door off my fathers fireplace by closing the glass doors almost all the way to get it started and leaving it that way too long. It got so hot, so fast, that one of the tempered glass doors shattered. It sounded like a gunshot in the house. That'll get your attention, I assure you. I oftern do this to get a fire going quickly, I just have to remember to open them after the fire gets big enough to self-sustain.