Data missing after field optimization

[sono-io]

	Hopefully I won't look like too much of a numbskull here but after reading some sites on
table optimization, I decided to remove the NULL as default on the fields in my products
table.  I thought everything went well until I realized that we hadn't received any
orders for 2 days.  That's when I realized that my products table was empty!  Luckily
this happened over the weekend.  =:\

	I've made changes to field types before and never had a problem like this.  Does anyone
know what went wrong from my limited description?  Why would removing the NULL default
cause data to be lost?

Thanks,
Marc