I am not sure if this is an Android 2.1, Sprint, Android Market App, or Samsung Epic problem. My Samsung Epic randomly restarts.
Does it restart on its own or do you have to pull the battery to power it back up? I ask because I had this problem and it was solved by removing the Lookout app.
I have the problem 2 or three tomes a week it restarts and I don't have either ot those apps on my phone. Occasionally I look at the screen and it black with red blue and black lettering next time I'll write down what it says. I don't seem to lose anything when this happens.
I have found that many people with Android phones have this problem: http://androidforums.com/evo-4g-support-troubleshooting/96897-evo-rebooting-its-own.html
I think I found to solution to fixing the random reboots. You need to remove and replace the battery while the cell phone is still on. This seems to hard reset the cell phone and eliminates or at least reduce the number of times the Samsung Epic randomly reboots. I read a post of another Android phone suggesting this procedure (they also described removing and replacing the SIM), but no SIM with Sprints Samsung Epic, so I removed and reinserted the microSD card.