Windows 7 search not showing results from mapped Server 2008 R2 share

Given that you're trying to search a server and not your local system, it's probably not related to indexing as you shouldn't have all your clients indexing a file server.

What happens on the system that doesn't work if you login as a completely different user and try to search the sever? If you get results, try the steps laid out on this site

There's a registry key:

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced

In this key there are two values (both hex dword)

Start_SearchFiles Start_SearchPrograms

Uninstalling Windows Search sets the value of both of these to zero, when they default to something else. However, reinstalling Windows Search does not restore them to their default setting like it probably should. By manually setting both of them to 1, it re-enabled the windows search function from the start menu. Somebody might want to notify one of the Microsoft software engineers that they should correct this issue so that reinstalling Windows Search properly configures this registry key back to its default setting, that way if anybody else does what I just did they'll avoid the same headache I went through. (I don't know how to contact them myself.)

Another thing to try would be to try the steps outlined on this site