See solution here:

http://rehmangul.sauftveyr.com/2008/04/23/can-not-add-the-user-because-a-user-with-that-name-already-exists/

Worked for me.

Here is a list of common illegal characters that must not be included in web urls – - – and not used when creating file names that will be used on the web:

# % & * { } \ : < > ? / +

In addition to this list it is prohibited to have consecutive periods in the URL (or file name). It’s also prohibited to start or end with a space or underline, or to end with a period.

Even though it isn’t illegal to use commas or spaces in a url – it is best to not use them for consistency across different server platforms.

These rules are Web Standards.

Important things too know about using TODAY in a calculated column!

http://www.linkedin.com/news?viewArticle=&articleID=185992482&gid=93094&type=member&item=28659782&articleURL=http%3A%2F%2Fblog%2Epentalogic%2Enet%2F2010%2F09%2Ftoday-sharepoint-calculated-default-values%2F&urlhash=q1qF&goback=%2Egde_93094_member_28659782

You need to edit a line of code in SharePoint Designer

• Go to Code View
• FIND:  “Placeholderleftnavbar”
• Delete Row (approx. line 47) that has that above code
• OK to Change site definition

Another GREAT tip from Christophe at Path to SharePoint

=IF([Status]=””,”Black”,IF([Status]=”Choice1?,”Red”,IF([Status]=”Choice2?,”Gold”,IF([Status]=”Choice3?,”Green”,IF([Status]=”Choice4?,”DarkBlue”,IF([Status]=”Choice5?,”DarkCyan”,IF([Status]=”Choice6?,”DarkRed”,IF([Status]=”Choice7?,”Gray”,””))))))))&IF([Status]=”Choice8?,”MediumSlateBlue”,IF([Status]=”Choice9?,”SpringGreen”,IF([Status]=”Choice10?,”MidnightBlue”,IF([Status]=”Choice11?,”Sienna”,IF([Status]=”Choice12?,”SlateGray”,IF([Status]=”Choice13?,”OliveDrab”,IF([Status]=”Choice14?,”Gray”,””)))))))

I’ve used this before. Great solution for collapsing a multiple-line of text field. Solution created by Paul Grenier and enhanced by Pater Allen.

Great idea from Jim Howard for creating section breaks in a Display Form or Edit Form.

Sometimes there are instances where page functionality is not operating as it should. The GUI is not letting you edit a page or remove a corrupt web part. Here I will start listing those URL appendices that will get you to the mode you need:

Put a page in EDIT mode.

Solution provided by Mehul Bhuva at SharePoint Fix.

How to Quickly get to the task pane of an ASPX page.

Add the following text to the end of the ASPX page.

?&toolpaneview=2