Some underscores (symbols) disappear when converting Word to PDF

[MeghaviNaik]

Hello!  We have seen several issues of Adobe not displaying some symbols (e.g. underscores) when converted from MS Word to PDF (using Adobe Pro).  We use Adobe plug-in in MS Word for the converstion.  

In Adobe, the underscores (symbols) are displayed when zoomed out to about 66.7%, but when we zoom in the underscores disappear.  Several onlines hint that this is by design with Adobe, but wanted to check here to see anyone has seen any viable workarounds and/or long term resolution.

[Karl Heinz Kremer]

When lines disappear when you zoom, the linewidth may be too small to be rendered correctly. When you go into Acrobat's preferenes, and go to the "Page Display" category, you will see some "Rendering" options. When you change these, does the display of these lines change?