A creature with resistance to energy has the ability (usually extraordinary) to ignore some damage of a certain type each round, but it does not have total immunity.
Each resistance ability is defined by what energy type it resists and how many points of damage are resisted. It doesn't matter whether the damage has a mundane or magical source.
When resistance completely negates the damage from an energy attack, the attack does not disrupt a spell. This resistance does not stack with the resistance that a spellmight provide.
Find topic in: Psionic, Rules of the Game
d20 Abilities & dnd d&d To SRD srd 3.5 Abilities dnd & Conditions d20 rpg Conditions Special d&d Conditions dungeons Resistance wizards Special Basics srd Basics Energy 3.5 Special roleplaying Special dragons dnd srd d20 d20 3.5 dragons Resistance dragons