I've experienced this problem 3 times now. It results from a transistor(s) in your memory chips not getting power to flip, and as a result, the file loaded into it, in your case, win32.sys, becomes unusable. There are a bunch of reasons why it could happen.
1. your MoBo isn't sending the signals properly to the ram. (not likely, you'd be experiencing other issues if it were)
2. your ram is faulty (again, not as likely, because it can stand memtest)
3. Your PSU isn't supplying enough power or the power is dirty(very likely)
Of the three times this has happened to me, upgrading my PSU has fixed it (one time I was able to keep it stable for a brief window of time by adjusting the voltage settings and . I reccommend a minimum 550w generic PSU with atleast 2 fans. try and spend as much as you're willing to on a PSU, even if it's generic. Dirty power (large fluxuations in voltage levels) can cause some nasty problems, too, very similar to what your experiencing. See if you can't find a helpful friend with a nice PSU to test it out with.