Are you using Tk::FontDialog?

from the docs:

CAVEAT
Note that font names with whitespace like ``New century schoolbook'' or ``MS Sans Serif'' can cause problems when using in a -font option. The solution is to put the names in Tcl-like braces, like

-font => "{New century schoolbook} 10"

in your case:
-font => "{Times New Roman} 10"

kind regards,