If there are more than 100 files in the “List of fonts” box when you try to install PostScript fonts to the %SystemRoot%\fonts folder, certain font files disappear in Windows Vista or in Windows Server 2008
On a computer that is running Windows Vista or Windows Server 2008, you right-click the %SystemRoot%\fonts folder, and then you select the Install New Font option to install some PostScript fonts. In the Add Fonts dialog box that appears, you browse to the folder in which the font files are located. (In the Add Fonts dialog box, you can select the fonts to install from the List of fonts list.) However, if there are more than 100 font files in the folder, for every 100 files that are added to the list, the first font file in the list disappears from the List of fonts box.
Notes For example, the first file disappears when there are 101 files. The first two files disappear when there are 201 files. The first three files disappear when there are 301 files, and so on.
For more information on this issue, including potential causes, workarounds, and resolutions, see: Microsoft KB Article KB967744.