This situation tends to happen when you had in one time or another relocated your Favorites folder on the same computer. Example, instead of leaving the folder in the "c:\users\..." directory, I placed my Favorites folder in "d:\data\favorites".

You may encounter error messages like "access denied" or "unable to add" and so forth. Vista simply refuses to let you add a bookmark to your Favorites. There is a solution to this.

To find out the reason for this happening, follow this link.

The solution is documented below in case it gets removed in the other website.

The solution is to set the integrity level (to low) for the relocated Favorites folder. This article has a detailed write-up, and also provides a script which can automate the setting for you. Use one of the two methods below:

Method 1
Download fix_fav_il.vbs and save to Desktop. Double-click the file to run it. Click Continue when you see the User Account Control elevation prompt. The script will open an elevated Command Prompt window and fix the integrity level setting automatically. Once done, you should now see this message:

processed file: favorites
Successfully processed 1 files; Failed processing 0 files

Type EXIT to close the Command Prompt window.

Method 2
1. Click Start, type shell:favorites and press ENTER. The Favorites folder of your user account will open. Copy the full path shown in the Address Bar.

2. Open an elevated Command Prompt. To do so, click Start, click All Programs, click Accessories, right-click Command Prompt, and then click Run as administrator.

3. Type the following command:

icacls <favoritespath> /setintegritylevel (OI)(CI)low
Note: Replace the tag <favoritespath> with the actual path to your Favorites folder, enclosed with double-quotes)

Example:

icacls "D:\My Favorites" /setintegritylevel (OI)(CI)low
You should now see this message:

processed file: favorites
Successfully processed 1 files; Failed processing 0 files

4. Optionally, to verify if the Integrity Level is correctly set for the Favorites folder, run the command below:

icacls favorites
You should see the following line in the output:

Mandatory Label\Low Mandatory Level:(OI)(CI)(NW)

5. Type EXIT to close the Command Prompt window.

You should be able to add an URL to Favorites now. Reportedly, this problem occurs as Internet Explorer in Windows Vista runs under Protected mode (low integrity level) by default, and therefore will only be able to modify objects marked with a low integrity level in their system ACLs. When you relocate the Favorites to a different drive, you need to set the integrity level for the relocated folder, so that Internet Explorer (Protected mode) can write to it. This problem does not seem to occur if the Favorites folder is located within your user profile home directory.