OK, solution was found, from this forum:
http://social.technet.microsoft.com/For ... f=requiredHere's the post (from KevinInNZ):
This happened on my Windows 7 PC and it was due to an install of Sourcegear Vault 3.0 that overwrites a registry entry used by many programs. The three it affected on my PC were Internet Explorer 8 (most links will not open), Windows Explorer (double click opens a new search window) and MS SQL Server Management Studio 2008 errors with COM error. This is all due to two registry entries containing {B8DA6310-E19B-11D0-933C-00A0C90DCAA9} overwriting the correct ones.
To fix this, save the info below into a reg file and run it to correct the registry entries on your PC. A reboot is required to get the double click working correctly in Explorer.
WARNING: Backup your registry or these registry entries below to be on the safe side.
[COPY FROM]
Windows Registry Editor Version 5.00
[HKEY_CLASSES_ROOT\Interface\{6D5140C1-7436-11CE-8034-00AA006009FA}]
@="IServiceProvider"
[HKEY_CLASSES_ROOT\Interface\{6D5140C1-7436-11CE-8034-00AA006009FA}\NumMethods]
@="4"
[HKEY_CLASSES_ROOT\Interface\{6D5140C1-7436-11CE-8034-00AA006009FA}\ProxyStubClsid32]
@="{A4A1A128-768F-41E0-BF75-E4FDDD701CBA}"
[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{6D5140C1-7436-11CE-8034-00AA006009FA}]
@="IServiceProvider"
[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{6D5140C1-7436-11CE-8034-00AA006009FA}\NumMethods]
@="4"
[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{6D5140C1-7436-11CE-8034-00AA006009FA}\ProxyStubClsid32]
@="{A4A1A128-768F-41E0-BF75-E4FDDD701CBA}"
[COPY TO]