Windows Vista Hard Drive Detection

[CleverStake]

Recently, I upgraded a friend's computer and operating system from Windows XP to Windows Vista. I ran into very few kinks until recently, when the new hard drive I added stopped working. Upon inspecting the problem, I checked the BIOS to find that the second hard drive was detected, but it only 'occasionally' is detected by Windows. I've been at a loss for what to do to solve the problem. As far as I can detect, all of the Windows drivers are up to date. ...And yes, I jiggled the wires: I wouldn't be coming to you guys if I didn't. Any suggestions? I know may not be the most appropriate section for this problem, but any help would be greatly appreciated from the experts. Thank you in advance.

 

[Hefemeister]

I know you jiggled the wires but have you tried different sata and psu cables and tried a different sata port on the motherboard?

 

[LA1]

did you initialise the hard drive
right click my computer
manage
then disk management
find the hard drive