File system problems with memory remapping

Hi

I have a PC based on a Asus Commando mobo, Core 2 6600 processor and 4 sticks of 2 gigabyte Corsair XMS memory (double channel configuration).
The installed OSs are XP Professional and Vista 64 bit.
Everything works fine enough until I try to set memory remap function: if I try Windows XP continues to work fine, but Vista gets crazy.
I start getting file system errors on C: drive and I cannot make simple operations like moving files.
If I try to restart the system it runs chdsk on C:
Sometime this can solve the problems, sometimes it cannot and I have to reinstall the system.
The problem does not change if I install Vista on another HD.

I have to say that the reliability monitoring function shows bursts of hw errors when I work on the PC under Vista (it happens without memory remap too) and that the problems with the file system sometimes happen without memory remap too, but in such situations chkdsk has always been able to recover the file system, up to now.

Can anyone help me? Thank you in advance

Timings are set by SPD, voltages are as per default.
I've run memtest86+: no problems without memory remap, i got errors with memory remap instead.
I've checked my memories: I have two matched pairs of Corsair memories, both XMS2, part number TWINX2X2048-6400G.
Removing two sticks, memtest is ok both with and without memory remap, however I still have bursts of memory errors in the reliability and performance monitor.

Bye