Windows 7: Can't add, delete or change user accounts

I have been working on a friends computer, trying to clean it up a little. I am logged onto the administrator account that he had set up, but it also shows it as a guest account and I can't do anything with the other accounts. I am trying to delete some of the standard user accounts that he doesn't want on it anymore and I can't do anything with them. When I try to create a new user account it shows
"The specified account name is not valid, because account names can not contain the following characters:/\[]";:|<>+=,?*
Please type a different name"



I have tried even entering just one letter at a time all the way to my name and it still comes up with that. There are just several crazy things going on with this and it is driving me crazy.

A simple Google search with;

The specified account name is not valid, because account names can not contain the following characters:/\[]";:|<>+=,?*

returned the following result;

http://www.techsupportforum.com/forums/f217/solved-creating-a-user-account-573258.html

There were many more, but the above link was the number one hit.

HTH

Method 1: Use the “On screen Keyboard” to type the characters and check if that makes any difference
Type without using the keyboard (On-Screen Keyboard)

Method 2: If your keyboard is equipped with an F-lock toggle key (FN lock key), turn it off and then check to see if the issue persists
F-lock toggle key might cause such issues.

Method 3: Check if this helps you to create a user account
a) Press Winkey +R to pull up run box
b) In the Open box, type in control userpasswords2, and then click OK.
c) Now check if you can create another user account by clicking on “Add” button on User Accounts window
If the issue persists,
d) Go to the “Advanced tab”, click on “Advanced” button under Advanced User Management
e) Now on the “Local Users and Groups” window, click on “Users”, right click on the blank area on the right pane and hit “New User” , check if this helps

Tried these and here is what I got
Method 1-Same Result
Method 2-No F-lock on
Method 3-There is no "Local Users and Groups" for me to look at.

Any other suggestions.

The following link is returned when using the search term in my earlier post;

https://www.google.com/search?q=Windows+7+The+specified+account+name+is+not+valid%2C+because+account+names+can+not+contain+ the+following+characters%3A%2F%5C%5B%5D%22%3B%3A%7C%3C%3E%2B%3D%2C%3F&oq=Windows+7+The+specified+acc ount+name+is+not+valid%2C+because+account+names+can+not+contain+the+following+characters%3A%2F%5C%5B %5D%22%3B%3A%7C%3C%3E%2B%3D%2C%3F&sugexp=chrome,mod=0&sourceid=chrome&ie=UTF-8

Read through the posts and see if there is a solution. I have no first-hand knowledge of the problem, so that's where I would go.

HTH

I have been searching google and so far every post I run across usually has me do the same things like that and they don't work. Any more ideas???

Sounds like the PC has corruption so I would begin by booting into Built-in Administrator Account - Enable or Disable - Windows 7 Forums

Try deleting all other accounts except the one desired.

Then work through these other steps to Clean Up Factory Bloatware.

If you run into further problems here are Troubleshooting Steps for Windows 7 which lead up to if necessary running a Repair Install or getting the superior Clean Reinstall which often is easier than trying to sort a bunch of corruption that has accumulated possibly without ever even having a Clean Reinstall - Factory OEM Windows 7 - the steps guarantee a perfect install if only the tools and methods given are used.