There are two possible causes for this behavior: 

1. The color for low priority dictations has been set to something different than black (default).

2. The worklist cache folder has been corrupted.

To resolve the issue, please follow the below steps:

1. First please navigate to "General Settings->Worklist->Dictation List" and check that the color selected for low priority dictations (0-3) is indeed black.

2. If not, move your mouse cursor over the list item for low priority dictations and left-click on the small arrow-symbol to open the Color Chooser.

3. Select black as the color of choice for this category of dictations.

4. Close SpeechExec and navigate to the following folder using Windows Explorer: C:\Documents and Settings\<YourUserName>\Application Data\Philips Speech\SpeechExec\DictCache

5. Delete all files in that folder.

6. Start SpeechExec again.