Very odd X/Y axis drifting, please help!

This is my first Prusa i3 and it's having this odd X Y axis drifting issue from day one. This is where I purchased it:
[www.electronicgeek.ca]

I've tried everything, making sure the belt tension is OK, the X and Y motors are not hot, just warm.

Host software: Reptier-Host 1.6.1
Firmware: Marlin 1.0
I've also tried both slic3r and cura slicers, tried printing from host and SD card and all got the same issue.
The first 2 to 3 layers is fine, but then the X and Y axis start to drift and eventually (at layer 7) it crashes to the opposite of the X axis.



This is the file I tried to print. I download the stl from [www.thingiverse.com]


This is the eeprom setting:


I watched the printing many times and didn't notice or hear the motor skipping. Is it possible a firmware issue? This is the only thing I haven't tried.

any help would be greatly appreciated!

Have you checked that the X and Y pulleys are properly tightened?

Maybe slippery pulleys are the cause.

Yes. I checked that as well. Set screws are tightened to the flat face...

The psu is 12v 20a. That should be enough for heat bed shouldn't it? Thanks