Suggestions:
Right click My Computer, Properties, Hardware, Device Manager. Locate the
entries for your hard disks and double click each entry. On the Policies
tab, uncheck Enable write caching.
You will see a performance decrease because of this, but if the corrupt
registry/user profiles problems cease, then you'll be certain of the cause.
Logon to another account with admin privilege and run System Restore.
Choose the most recent restore point and SR should restore the user
hives.
Or...
Boot into safe mode and log in as Administrator. Copy ntuser.dat from
%windir%\repair to "Documents and Settings\[your user id]". Now do a system
restore to a point in time prior to when the corruption message began to
appear.
Or...
Relocate NTUserdat
Look in HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows
NT\CurrentVersion\ProfileList and find the profile you want to change and
then change ProfileImagePath to the ntuser.dat folder that you want to use.
You must manually copy or move the ntuser.dat file there.
Corrupt Hive
http://www.kellys-korner-xp.com/xp_sys32.htm
How to Recover from a Corrupted Registry
http://support.microsoft.com/default.aspx?scid=kb;en-us;Q307545