seanmcken, try typing:

sudo kernel-config limits 250 600
sudo kernel-config load lv

First will restore max frequency to 600 (as it should be).
Second will be a little undervolting without SmartReflex.

You didn't answer about your battery... Anyway, N900 is quite power-hungry. Managed to get less than 3hrs on cheap chinese Gold battery (1300mAh) for N900 overclocked to 900Mhz @ ulv profile (that's same voltage at 900MHz as stock 600MHz, and slightly less at other frequencies) while it was loading torrents via crappy 2G connection. If you use microB, especially with adBlock, it will get hot and may discharge even faster.