Two things: You'll probably get fewer reboots if you raise your minimum clock speed to 480. There's considerable discussion in this and other threads about clock speeds, but a good general rule is to start with 480/600 and explore other values carefully. (When I'm at 480/600, I don't get reboots or other such problems.)
Second: the Conservative governor is probably not suited as well to mobile devices as it is to certain kinds of desktop or laptop computers. I think there's a thread on XDA that discusses in depth most of the available governors and their benefits, but you're probably best off using one of those specifically crafted for mobile devices, such as SmartassV2, InteractiveX, SavagedZen. I think there are a few others, but Conservative, OnDemand, Performance, and Powersave were designed with desktops, laptops, and servers in mind, not mobile devices.