Random boot problem, missing drive

[ualdriver]

ASUS P6X58D-E motherboard
Windows 7 64 bit
Core i7 processor
Corsair 750 Watt power supply
WD Raptor 74GB
WD Velociraptor 300GB
OCZ Vertex 2 120GB
6GB Corsair Dominator RAM
HD 5870 graphics card

I built this system a few months ago, and it worked great until recently. The problem started where Windows would boot up normally, but my E storage drive (WD 300GB Velociraptor) would "disappear" and not appear in the library as an available drive. I opened up the machine, checked the connections and all appears well. But it is still doing this "missing E drive boot" about 50% of the time. I don't know where to start......mobo problem? drive problem? Windows 7 problem?

Today, the problem got slightly worse, or perhaps it is an unrelated problem. The computer now hangs on the mobo's splash screen after loading "ASUS express gate." I had to shut the computer down about 3 times before I could get the computer to get past the splash screen and boot Windows 7.

Any advice appreciated.

Thanks.

 

[rob_n86]

Sounds like the HDD might be crapping out, chkdsk. Do you have windows 7 partition and the 100mb system reserve on the same physical drive?

 

[ualdriver]

Sounds like the HDD might be crapping out, chkdsk. Do you have windows 7 partition and the 100mb system reserve on the same physical drive?

No, I have each drive as its own partition.

Is there any way I can definitely determine that is the hard drive failing? Is there a test or something I can do? I think it might still be under warranty.