Need help to root-cause BSOD (Stop code: 0x50) in ntfs.sys

[windoh7]

Trying to chase down this persistent BSOD on my dad's new Acer laptop. System is largely unusable (except in safe mode). BSOD's soon after boot-up/login.

BSOD screen text:

ntfs.sys
page_fault_in_nonpaged_area
stop: 0x00000050 (0xfffff98102dc26a0, 0x0000000000000000, 0xfffff88001c284e0, 0x0000000000000005)
ntfs.sys - address fffff88001c284e0 base at fffff88001c1d000, datestamp 4a5bc14f
locale ID: 1033
OS version: 6.1.7600.2.0.0.768.3
bcp1: fffff981104026a0
bcp2: 0
bcp3: fffff8800161a4e0
bcp4: 5
os version: 6_1_7600
service pack: 0_0
product: 768_1

System info:
Acer AS5741-6073 Laptop
Intel Core i5-430M Processor (2.26GHz)
4GB memory
500GB WDC hard drive
Microsoft Windows 7 Home Premium (64-bit)

Dumps attached...

Things I've already tried:
- memtest86 : No problems reported
- chkdsk - Reported and (claimed to have) fixed an issue of free blocks being marked as allocated. But the BSOD persists even after this.
- Safe mode: system generally usable with usual safe mode limitations (i.e. no immediate BSOD soon after boot). But will BSOD if I attempt to do a system restore to an earlier save point.

Appreciate any help...

 

[windowsapple]

Contact Acer!