There have been reports of font problems when using Version 5.5 (or earlier) after an update to Windows 10, in particular the Windows 10 Creator update.  The reports are that the minus sign does not look right, and that Calligraphic and Blackboard Bold characters do not appear correctly in the edit window.  When typesetting for DVI, text does not appear in the TrueTeX Previewer.

NOTE: The rest of the article goes into more detail, and then refers to Document 448 for even more details.  The quick fix that seems to work is to use File Explorer to navigate to the directory TCITeX\fonts\truetype below where SW is installed (c:\sw55 for Scientific Word or c:\swp55 for Scientific WorkPlace).  Highlight all the .ttf files in the directory.  Right click and select Install from the menu that appears. You may get a dialog that says a font is already installed; reply Yes to replace the existing font and turn on the check box to do this for all  remaining items. Repeat the steps in the directory TCITeX\fonts\truetype\eurosym.

Apparently the new update does not allow by default the installation of fonts by using shortcuts.This is the method used by the TrueTeX installation program.  A possible work around to correct this is to set Windows 10 Creator to allow fonts to be installed using shortcuts.  Use the Windows Fonts applet to change the font settings to allow installation using shortcuts, as shown by this screen capture:

After making this change the fonts need to be restored.  The usual easiest way is to run the SWP install program and use the Repair selection that will be available.  The fonts can also be copied to the Windows Fonts directory.  See Document 448 for more details to repair fonts.

Update:  Looks like Microsoft sees this as a problem with the font cache.  See this article from the Microsoft web site:  Fonts installed by using “Install as shortcut” are missing after a system restart in Windows 10 Creators Update