I think you could be wrong about this. You say this "implementation" does not support real 64bit. But did you emanate, that I don't got the same motherboard as weVeg mention? Thinkpad X1's are made with many different models like many other manufactory lines. My chipset does support SandyBridge, but I got no idea if the one WeVeg got supports it. Could maybe be relevant? Is it still pseudo 64bit? I might say that I've now tried the 32bit version and the problem consists...
I can be wrong for sure, but the fact is, in my knowledge I know that real 64bit intel cpu are xeon and/or itanium stuff...
with this I mean, in this case a CPU might have external data buses or address buses with different sizes from the registers, even larger. The term may also refer to the size of low-level data types, such as 64-bit floating-point numbers but not instruction set. It was a long and old discussion that we had somewhere else in community wide, I don't remember now the details....but anyway, let come back to your problem.
Please check my specs again:
CPU Intel® FCPGA988 Socket Supports Sandy Bridge Processor
BIOS AMI 8Mbit SPI BIOS
System Chipset Intel® QM67
I/O Chip Nuvoton NTC6776F
System Memory One 204-pin DDR3 SODIMM Socket Supports Up to 8GB DDR3 1066/ 1333 SDRAM
SSD 1 x mSATA (from Mini PCIe Slot)
Watchdog Timer Reset: 1sec. ~ 65535min. and 1sec. or 1min./step
Expansion 1 x Mini PCIe (Support mSATA)
I/O
MIO 2 x SATA III, 1 x RS-232, 1 x RS-232/ 422/ 485, LPC
IrDA Nuvoton NTC6776F (Share with COM2)
USB 10 x USB 2.0
DI/O 8-bit GPI, 8-bit GPO
Display
Chipset Intel® QM67
Display Memory Share System Momory Up to 512MB
Resolution DVI Mode: 1920 x 1200 @ 60Hz, LCD/ Simultaneous Mode : 18 or 24 bits/pixel; Pixel Clock 25-112MHz, HDMI Mode: 1920 x 1200 @ 60Hz
LVDS Dual-channel 18/ 24-bit LVDS
Multiple Display DVI + LVDS, DVI + HDMI, HDMI + LVDS
Model: Lenovo Thinkpad X1
CPU: Intel Core i5 2520M 2,5 GHz
Graphics: Intel HD Graphics 3000
HDD: Samsung 830 Series 280 GB SSD
Memory: Corsair 8 GB DDR3 SO-DIMM RAM
I think it's lacking compability... But maybe I'm wrong. 
EDIT: BTW, I got Windows 7 Enterprise 64Bit and it works perfect. It's beeing delivered with 64bit Professional...
Can you check the X log files and the system logs as well if there are any suspicious logs related to pad?
Because I have a lenovo (l420 64bit) as well with similar specs of yours and haven't noticed any problem regardless.
Could be pointer problem in x configuration file.