Windows Vista – dialog box hangs

Try using this tool (found in this thread). It will display if any application has a "lock" on the clipboard.

A similar problem was treated in the following thread : HgTortoise in Vista 64-bit not showing the context menu.

There, the accepted answer was a way to run 32-bit windows explorer on Vista 64-bit using the command:

%Systemroot%\SysWOW64\explorer.exe /separate

A later update to the thread said:

Update: TortoiseHg 0.8 (released 2009-07-01) now includes both 32 and 64 bit shell extensions in the installer, and also works with Windows 7. The workaround described below is no longer necessary.

So it seems that your problem is that some products simply install only one version of the extension, either 32 and 64 bits. This is normal, since 32-bit shell extensions cannot be loaded into a 64-bit Windows Explorer, and vice-versa.

A solution would then be, for each such product, to find the missing shell extension 32/64-bits version and to install it in its proper environment.