We have the same problem on a single machine using Wildfire 4 and Windchill 10. Windchill interface looks fine in standalone browser but all text is tiny as shown above in the embedded browser. PTC's only recommendation was to upgrade to Wildfire 5.
We have no solution
1) removing and reinstalling Pro/E did not fix
2) adjusting settings in graphics S/W (nVidia) did not fix
3) embedded browser does not respond to <ctrl +> or <ctrl -> like the standalone browser does
4) deleting cache (AppData\Roaming\PTC\ProENGINEER\Wildfire) did not fix