boot some times, some times not

[kevkalv]

thinkpad 2645-35u, put new hard drive in ,40g hatachi,228 ram, xp pro sp2...this thing boots fine . the next time i boot it gets error 1780 hard disk error. the drive tests good when it works, and shows up in the list.
tests bad but shows up still . then it will boot again, have latest bios, worked fine with ram upgrade this is inntermittant. it also is very stable while running, no lockups ,and fast for what it is ....help

well my other drive works great so my new 40g is bad . still runs good when it boots and tested perfect till the little gremlin gets it, strange will send it back to where i got it for replacement, by the way ,love this forum