I have seen similar strange looking things before. They usually occur when trying to display characters or symbols that your computer isn't set up to display. An "Em-Strich" is a dash with the width of the letter "M" which is the widest letter in the alphabet. Perhaps your computer is trying to tell you that there should be an extra long dash after the "&". Or perhaps the combination of "&" and "mdash" means some other symbol entirely. There are some other different lengths for spaces and hyphens or dashes too. The "ProZ" display system is not the same as the German characters and symbols on my computer with MS-WORD, so it will not do any good to try to show the differing lengths here. You can find them under "symbols" in the "insert" menu of MS-WORD or I could send them to you as a MS-WORD attachment to an email. Here are the translations without the visuals:

no space = keine Leertaste
¼ Em-Abstand = ¼ em space (slightly shorter than a normal space)
normal space = Leertaste
hyphen = Bindestrich (slightly longer than a normal space)
En-Abstand = en space ≈ lowercase "n"
Gedankenstrich = En-Strich ≈ en dash ≈ lowercase "n"
uppercase "M" (on my computer with MS-WORD, this is appears to be slightly smaller then the following two)
Ceviertstrich = Em-Strich ≈ em dash ≈ uppercase "M"
Em-Abstand = em space ≈ uppercase "M"

HTH - Dan