sounds to me like they are not plugged in very good.
unplug everything...and inspect eh ide sockets, and the molex connectors..
inspect the cables, and then plug them in, and make sure that they are plugged in very good, and secure.
i had a problem like this last night, and i narrwoed it down to the hard drive cable being REAL sensative...and if it gets moved....then it crashes..
so check that out, and narrow it down...
-Live, Learn, then build your own computer!-