The semicolon is indeed a comment character and the second should not affect anything.
Wowexec and NTVDM will stay loaded after called by 16bit software. This is normal. Both should appear in the task manager process list. When this problem occurs, is Jeppview listed in the process and applications tab of the task manager?
If it is, try highlighting Jeppview and clicking the Switch-To button. (You may have already tried this). Alternatively you could try ALT-Tab to see if the window is hidden.
A shot in the dark:
Rename Win.ini and kill the wowexec & ntvdm processes and try Jeppview again.
Second shot:
Reinstall Jeppview in a new directory from XP.
Sorry about the earlier assignment, BOAC and Good Luck!