I tested this again. At first the problem remained the same but after I had to restart my Windows 7 Ultimate SP1 in order to install the latest Windows service fixes, I then was able to access the Windows Explorer and MS Word seamlessly. So at least in my case, it started to work after my Windows 7 Ultimate SP1 got the latest Windows service fixes installed.
I tested this again. At first the problem remained the same but after I had to restart my Windows 7 Ultimate SP1 in order to install the latest Windows service fixes, I then was able to access the Windows Explorer and MS Word seamlessly. So at least in my case, it started to work after my Windows 7 Ultimate SP1 got the latest Windows service fixes installed.