Yes, this can happen, but there are a few things you can do;
Option 1: Lock MSN Messenger
- In the main Messenger Window Click on Plus at the top
- Click on Lock Messenger
- Messenger Plus will now let you set up a lock on MSN Messenger, with a password
- MSN Messenger will be locked, meaning you will need a password to do anything
- When you need to use MSN Messenger again, double click on the icon in the taskbar, and you will need a password (which you just set up) to use it.
After setting up a password you can also set up a key combination which lets you lock MSN Messenger, in future, with the press of a few buttons.
Option 2: Lock your Windows Session
You could also lock your windows session, there's different ways to do it on every version of Windows. Assuming you use XP, you can find many ways to lock your Windows session here -
Different Ways to Lock Windows XP.
Just make sure you set your windows account with a password;
- Start > Control Panel > User Accounts
- Click on your account
- Click on create a password
- Follow the screen through, and set up a password, when done click on Create password.