@gmw: How much time does it actually take? (To cold boot, and to restart nickel on KOReader's exit).
Because if all is well, a restart should take less than 10s. When it takes a bit longer, it usually means that I did something wrong ^^ (or that Nickel is in a mood).
EDIT: I'd also ask you for your KOReader version, but with a H2OČr2, it's got to be pretty recent anyway

.