MKV runtime length not being shown in folder Detail mode.

I just got done reinstalling Windows 7 Professional 64 bit. Before I did the reinstall, it would display the runtime length of MKV files when I would open a folder in Detail mode. As I recall, accomplishing this the first time was not easy. It's proving difficult again. Here is what I have done:

Immediately after the reinstall, absolutely no runtime lengths were shown for any kind of video file. I installed the latest K-Lite codec mega packs for both 32 bit and 64 bit. The runtime length of every video format is displayed - except for MKV.

After doing some research, there were those (including those who claim to be affiliated with DivX) who said the DivX codec pack was designed to add the MKV length functionality to folder listings - so I installed that - no joy. (My prior experience with DivX and "locked" MKV's caused me to pause before proceeding with the above step. Its failure led me to then uninstall DivX).

More research found those who said using Win7DSFilterTweaker to set the preferred decoder to ffdshow would solve the problem. I did this for 32 and 64 bit (one at a time, individually and together); the problem remained.

Others said that using it to set the 64 bit preferred decoder to LAV would work - it didn't.

One person claimed that installing Haali Media Splitter fixed the problem on his system - but not on mine.

Oddly... the K-Lite's Codec Tweak Tool's "Miscellaneous:" "Thumbnails" options did allow me to force Windows 7 to display a thumbnail in the status bar when an MKV is highlighted - but still no runtime length display.

Anyone have any ideas about other possibilities to fix this annoying problem?

Edit: Oh yeah... I also tried installing x264vfw - no luck there either