Hi Nick,
See if this applies:
Scheduled Tasks Cannot Run with a Blank Password [Q310715]
http://support.microsoft.com/?kbid=310715
Also, from MVP Kelly (a workaround):
For Pro: Start/Control Panel/Administrative Tools/Local Security
Policy/Local Policies/Security options.
In the right hand pane (third down). Accounts: Limit local account use of
blank passwords to console logon only. This is enabled by default, disable
it.
For Home: Backup your registry before modifying. Locate the following
registry key:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa
Value name: limitblankpassworduse
Type: REG_DWORD
Data: 0 (disabled) 1 (enabled)
It is enabled by default. Disable it and scheduled tasks should run.
As to defrag, you may also like this from Kelly:
http://www.kellys-korner-xp.com/xp_tweaks2.htm#util
Under the utilities dropdown there is a link to "defrag all drives as a
scheduled task".
--
Best of Luck,
Rick Rogers aka "Nutcase" MS-MVP - Win9x
Associate Expert - WinXP - Expert Zone