Vista - Any ideas on Out of Sync problem?

Hi everyone, first let me tell you that this next problem I've had
ocurred on both 5600 for x86 and x64. My system specs:

Intel Pentium D 945+ @ 3.4Ghz
ASUS P5ND2-SLI with Nforce4 SLI Intel Edition Chipset
2Gb DDR2-533 Kingston Memory
XFX GeForce 7900GT 256Mb Graphics Card
2xSATA-II 160Gb Samsung Hard Drives
Primary Display: Viewsonic VX2025wm, Secondary Display: Viewsonic VX924

Installed Vista everything working fine, at the end of the installation
and starting for the first time, I manually extend my desktop to the
second monitor (In Beta2, the desktop extension was automatic), my
Primary display goes out of sync. Only the secondary display shows the
desktop.

Changed the primary to secondary (via control panel, no Nvidia Beta
drivers installed yet) and now the VX924 is the one to go out of Sync,
showing me only the desktop (no icons or anything) on the primary display.

Installed Nvidia Beta 96.33 Drivers, and exactly the same thing
happened, installed also Nvidia Beta SMBUS drivers, and nothing
happened, I cannot see the actual Refresh Rate mode since on the working
display nothing shows but the desktop wallpaper.

Any input about this or how to solve it would be very appreciated.

Thank you in advanced.