An Office program is slow or may appear to stop responding (hang) when you open a file from a network location.

To do this, follow these steps:

1. Close your Office programs.
2. Click Start, and then click Run.
3. In the Open box, type regedit, and then click OK.
4. Locate, and then click to select the following registry key:

   Office 2003

   HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Common\Open Find

   Office 2007

   HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Common\Open Find
5. After you select the key that is specified in step 4, point to New on the Edit menu, and then click DWORD Value.
6. Type EnableShellDataCaching, and then press ENTER.
7. Right-click EnableShellDataCaching, and then click Modify.
8. In the Value data box, type 1, and then click OK.
   
   Note Any non-zero number in the Value data box will turn on caching. A zero number or blank (default) will turn off caching.
9. On the File menu, click Exit to quit Registry Editor.

Source