And Again - Error ID 333 - An I/O operation initiated by the Registry failed unrecoverably.

Hi All

After months of diags, registry checks, hotfixes and hours spent to try to fix this problem, I'm here to submit it to you all

Problem is know on this forum, but never was really fixed if not use a night reboot (that is not a solution, just a workaround)...

This is the Complete error:

Event Type:      Error
Event Source:      Application Popup
Event Category:      None
Event ID:      333
Date:            18/04/2012
Time:            3.13.00
User:            N/A
Computer:      xxxxxxxxx
Description:
An I/O operation initiated by the Registry failed unrecoverably. The Registry could not read in, or write out, or flush, one of the files that contain the system's image of the Registry.

For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.
Data:
0000: 00 00 00 00 01 00 6c 00   ......l.
0008: 00 00 00 00 4d 01 00 c0   ....M..À
0010: 00 00 00 00 4d 01 00 c0   ....M..À
0018: 00 00 00 00 00 00 00 00   ........
0020: 00 00 00 00 00 00 00 00   ........

As you can see in the attached image, it happens so many times on System Event log and ANY CHANGES to SAM become impossible, no user can change password or add/delete new users, groups and so on

As I told before, I spent weeks over google to try to fix and my last try before write here was reinstall Windows 2003 from scratch and move all over here, in a week the problem returns itself

Some Tech details on server:
It's a Windows 2003 Standard edition 32 bit
avast! Server Business Protection
IIS6 with a huge number of websites
Backup Exec 2010 Remote Agent Utility

Hardware is based on a brend new
Dell R610
Dual Xeon Quadra Core
4 GB RAM ECC
Perc 6i with 6 x 146 HDD in RAID5

I hope somebody can help us to fix :(

Thanks
Mauro
ErrorID333.png