Weird stuff with my sata300

I recently bought myself a new computer...piece by piece.. and there seems to be something wrong with my sata drive (maxtor sata300 250 gb 16mb diamond max 10). well...from time tot time.. my computer just doesn`t see my hard .. and this happens when i start my computer or when i restart it. I get the typical disk boot failure message... and not even my bios doesn`t see it at this moment..
Well..the weird part is that..all i have to do to get it fixed...is to remove the data cable from my drive...and to put it back on ... wtf? this is getting pretty annoying.. this day i had to bend my back 4-5 times.. isn`t this cruel?

any ideas?
tried choosing another sata slot...tried new cables.. temperature looks ok (47 Celsius)..tried asking some friends ..what to do?


my system:
amd athlon64 3500+ 200mhz
artic cooling freezer 64 pro 2200rpm
EPOX nFORCE4 SLI/ SK 939/ 4xDual channel DDR400/ 2xPCIEXP16x/ 1xPCIEXP1x/ 8CH/ Gigabit LAN/ SATAII/ ATA133/ ATX
xfx geforce 6800xt 256mb 256bit
2 x geil 512mb
maxtor 250gb 16mb sataII diamond max 10
ans 450 watt case

Pleeeeeease help...