Avast 5 beta3 update error on Windows Vista

Hi!
I’ve just updated my Avast 5 beta3 and, when I reboot, Windows give me this error: 0x00000050 (0xAC72B000 0x00000000 0x83B3QB6 0x00000000) PAGE_FAULT_IN_NONPAGED_AREA. What’s wrong? How can I solve?Do I have to get the non-updated version of Avast5?
Thank you

Some sort of data error, if you have the mini dump you could use the windows debugger tool the scan it and find the cause.