I copied this from somewhere on the web, see if it leads you anywhere.
"Subject: Setting Restricted Login Hours on XP Standalone System
I recently had to contact Microsoft Tech Support for assistance on this so I wanted to post the article on the web incase someone else had this same issue.
Situation: You want to restrict the logon days / times of a user account in XP and are a standalone machine.
Reason: You may wish to restrict teens who arrive home before adult supervision from accessing your broadband always on connection, limit employees to only work hours access etc..
Steps:
To Set restrictions:
Click Start
Click Run
Type cmd in the run box and press enter.
The following is a sample of what you would type:
net user testuser /times:M-F,5pm-9pm; Sa,6am-9pm;Su,6am-9pm
Where testuser is the local account name.
To Remove Restrictions:
Click Start
Click Run
Type cmd in the run box and press enter.
The following is a sample of what you would type:
net user testuser /times:all
Where testuser is the local account name."
137978 - Using NET USERS to Manage Local User Accounts on a Workstation
Typing NET HELP USERS | MORE at a command prompt will give you the list of options and syntax.
What records of logon and logoff times have you got in your Event Viewer, have you looked in there? Use the Security Log and use the Filter option to narrow down your search.
This is an example of what is in there.
Event Type: Success Audit
Event Source: Security
Event Category: Logon/Logoff
Event ID: 528
Date: 4/10/2003
Time: 8:06:43 AM
User: xxxx
Computer: xx
Description:
Successful Logon:
User Name: xxxx
Domain: xx
Logon ID: (0x0,0x11760D)
Logon Type: 2
Logon Process: User32
Authentication Package: Negotiate
Workstation Name: xx
Logon GUID: {00000000-0000-0000-0000-000000000000}