"Security log on this system is full" error when logging in

If you're logging in to a Windows XP or Windows Server 2003 machine and you notice this message, it's a really simple fix assuming you have access to an admin account on the machine. If not, you won't be able to login until it gets resolved, so contact an admin. Here's how to fix it:

1. Login using an account with admin privileges on the machine in question
2. Right-click My Computer, then go to Manage
3. Go to Computer Management->System Tools->Event Viewer
4. Right-click on Security and select Properties
5. In the Log Size section, do one of the following:

• Increase the maximum log size. This will avoid the error message until your log reaches the new maximum, but you won't lose record of any security log events
• Select Overwrite events as needed. This will maintain the log up to the maximum size, and then delete the oldest events when it needs more space
• Click the Clear Log button in the lower right. This will wipe out all records in your security log

6. Click OK

That takes care of the problem. You'll want to make sure to choose the best option for what you'd like to accomplish, and can use a combination such as increasing the log size and overwriting events as needed.