***There is a issue with the design of this light***

It overheats and goes into a death mode, which is a very dim flickering light that cannot be shut off. You have to remove the batteries and let it cool for 20mins. It only takes about 10-40mins for it to overheat depending on ambient temp. I got stuck in the woods with no light. NOT GOOD

I just got back from a 4 day trip using my light with no problems. I had the light on average about 20-30 minutes at a time every night. A few weeks ago I was also with a group and a few other people had this light as well and had them on well over an hour plus and there were no issues. What kind of temperatures were you in?

I have one of these with the same problem, and we're not alone. According to the reviewers at backpackergeartest.org it isn't a heat issue but occurs when the batteries are running low, due to the circuitry used in the switch, which also dramatically reduces the burn time in normal use ie switching modes/on/off as opposed to continuous use. 1-4hours - very poor. This correlates with my experience.
Good news - there is a new version in 2011 which might fix this - no tests/reviews that I've seen yet, but the rep in live chat said this is the 2011 version and they have fixed the problem.
Meanwhile, for old models the 'solution' is to put new/charged batteries in. Leaving them out for a while provides a temp fix for low but not quite dead batteries.