Hi Italian_Stallion
What kind of eggs are they? Have you moved them by hand, or otherwise touched them?
I raise corydoras and, probably like all eggs, sometimes they get fungus. I'm lucky that the eggs usually hatch in about 4 days and that's quick enough to keep it from spreading one to another.
The most common cause of fungus in cory eggs is that some are not fertile. These, since they aren't alive, just fade away and fungus just devours them. Damage, in any way that could make them nonviable, could have the same result. These things you will have little or no control over.
Other than that, most eggs need adequate water circulation over them. This washes away bacteria and microscopic debris that could damage them and result in a fungus attack. Corys need very strong water circulation, but other fish have different requirements. In the case of gouramis and bettas, for example, the male cleans the eggs himself so moving water, which would break up their bubble nests, is not needed. I would suggest looking into the specific needs of your fish in the forum dedicated to them.
Methylene blue is sometimes used by aquarists to prevent fungus, but IMHO, nothing works as well as carefully duplicating the conditions required by nature. If your fish require water circulation around them, no chemical will take its place.