This happened to me when I was deleting unnecessary clients.  I organized the clients in download / transfer from last year, so those clients that did not return were readily identifiable.  So... I was using the control key and the scrolling wheel at the same time and it caused the Homebase font to get exceedingly small.

The solution is to hold down the Ctrl key and scroll up one or two bumps at a time on the scrolling wheel,  AND wait for the program to catch up internally.  The fonts will start to expand.  (There seems to be a 3 second delay.)

If you move too fast, because you are impatient, and you first use the Ctrl key and the scrolling wheel moving back and forth,  it screws up the system and you get really large fonts, then small fonts, then large fonts.    The key is to move slow.