There is a feature when SharePoint user can open a document from Document Library for editing and click on "Save as.." to save the document directly to the library The problem is that the user gets the window to enter his credentials, but after entering his username and password, the user cannot pass the security and save the document.
After some research I found many post about this issue, I took most information from Microsoft link, and made instruction with images for this. I tried many times in different computers and it helped me.
More details about the issue you can find here:
http://support.microsoft.com/?id=943280
Here is a step by step instruction that helped me:
HOTFIX: http://support.microsoft.com/?id=943280
SYMPTOMS
You are prompted to enter your credentials, even though the user account that you are using has sufficient permission to access this site.
For example, when you open a Microsoft Office file from a Microsoft Office SharePoint site by using 2007 or 2010 Microsoft Office, or after you opened document from Document Library in SharePoint 2010 and try to Save as, or you (user) try to edit document and enter the hyperlink in Excel file cell on a Windows Vista-based or Windows 7 client computer, you are prompted for authentication.
RESOLUTION
Restart requirement
You have to restart the computer after you apply this .
Registry information
To use this hotfix, you have to modify the registry.
! Make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry.
! ( for more info read http://support.microsoft.com/?id=943280)
Follow these steps:
1. Click Start, type regedit in the Start Search box, and then press ENTER.
2. Locate and then click the following registry subkey
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WebClient\Parameters
3. On the Edit menu, point to New, and then click Multi-String Value.
4. Type AuthForwardServerList, and then press ENTER.
5. On the Edit menu, click Modify
6. In the Value data box, type the URL (http://*.yourcompany.com) of the server that hosts the Web share, and then click OK.
Note: You can also type a list of URLs in the Value data box. For more information, see the "Sample URL list" section in this article.
7. Find BasicAuthLevel registry key and change Value data from 1 to 2.
Note The mapping is as follows:
0 - Basic authentication disabled
1 - Basic authentication enabled for SSL shares only
2 or greater - Basic authentication enabled for SSL shares and for non-SSL shares
8. Exit Registry Editor.
Note: You have to restart the WebClient service after you modify the registry.
1. Click Start, type Services in the Start Search box, and click on Services.
2. Find WebClient and click on Restart
3. Restart your computer.
Know you could save document directly to SharePoint Document Library:
Note: If you cannot see the Document Library as at last picture, check User Accounts > Credential Manager > Windows Credentials. There should be SharePoint AD User Account, if no create it.
I hope this information will help you.
