make sure you chill them 48 hours before opening. it takes a while for the CO2 in the headspace to get absorbed.
it sounds like you may have:
a. over primed
b. bottled too early (fermentation not done)
c. have an infection
d. just need to let it chill longer in the bottle
if they still gush after chilling 48 hours, but taste ok, then its a or b. and if its b...you might have exploding bottles soon.
ask me how I know...
Primary: English Mild
On tap: Pale Ale, Lancelot's Wheat, English Brown Ale, Steam Beer, HoovNuts IPA
Bottled: MOAM, Braggot, Raspberry Melomel, Merlot, Apfelwein, Pyment, Sweet mead, Cabernet
Gal in 2009: 27, Gal in 2010: 34, Gal in 2011: 13, Gal in 2012: 10