Try substrings...
If usrName.Substring(0, 4).ToUpper = "BUT_" Then
Me.uiButRestButton3.Visible = True
...
Substring(STARTING POSITION, NUM OF CHARS TO RETURN)
All strings start at 0, so for the %CON_% instance, you will need to determine where in the string CON_ starts...
For instance: USCON_MYID
usrName.Substring(2, 4).ToUpper = "CON_"
If the position of the keyword is not always constant in the username string, you could take the high road and use the .IndexOf string property to determine if the keyword is in that string... anywhere.
Another thing is... are you sure you want to disable the view property or just disable the ability to click the button? button.Visible = False vs button.Enabled = False