"My son was 5 years old, and he needed to start school, so I wanted some stability" the now 40-year-old O'Riordan explains.
"I guess it was quite obvious that I would put my kids first and stay at home and spend time with them and be a full-time mother and enjoy the magic of being with my kids."
But, nine years on, her kids are now 7, 11 and 14, and much more capable of dealing with a mother on tour for several months, she laughs down the line from LA.
The band are in the midst of press interviews for the release of their sixth studio album, Roses (out this week) and the corresponding world tour, which sees them return to New Zealand to play Trusts Stadium on March 15.
The rest of the band were also in a position to be able to consider touring again, and when they got back together briefly in 2009 to celebrate O'Riordan becoming an Honorary Patron of the University Philosophical Society in Dublin, it seemed natural to think about picking up where they'd left off.
"It was very quick, and organic. We hadn't lost that chemistry and we all realised that we still had something beautiful and that we were very lucky to have accomplished what we had accomplished when we were younger. We thought we should do it now before we do get too old, if you leave it too long, you might never go back.
"So we just thought, let's go for it, just jump."
Despite the fact that O'Riordan has released two solo albums during the band's hiatus, her kids haven't really been aware of her status as an international pop star until recently, and none of them have any musical leanings or desires to follow her career path.
"I've mostly kept them away from my life as a musician and they don't really know anything about it. The younger ones only found out recently. When we stopped [in 2003] my little boy was only 5, and my first girl was 2, so they didn't know anything about it really. So when we did the reunion, the kids were like 'ah ... are you in a band or something?' They realised I was doing it for a long time, but they still see me as Mum."
The new album also draws inspiration from family, with the title track Roses written for her father, who died in November after a six-and-a-half year battle with cancer.
"In May when we were recording the album, Noel gave me the music for Roses, and it took me about 20 minutes to write the lyrics, and I was quite sure about it. And it was very sad, and I found it really hard to sing it when I first tried to get it down in the studio, I was shaking and very teary, and it took me a while to come to terms with it and settle down.
"You go through something like that and you really do realise that life is like a garden of roses, it's beautiful, and you need to embrace the good times and celebrate the good times when you have them."
Roses is a more subdued and contemplative than the hits the Cranberries are known for, like Zombie or Linger, and the whole album is a more reflective affair, with long-time producer Stephen Street keen to dig out a more intimate atmosphere.
"We did talk about how I could relax more, that it was okay not to be loud, that you don't have to be trying to project all the time, it's okay to be vulnerable, and soft, and so I found that thing that I think I lost after we went big with Zombie and so on, and I was pushing my voice quite hard. This was more about just being in the moment, and enjoying it, and yeah, it is okay that there isn't a big chorus or a big hook, you know, that doesn't matter, just paint your painting. Don't worry what is going to happen and whether the songs are commercial and catchy, just do it for yourself."
Veterans of the live circuit, they'll be looking to satisfy themselves and their fans as they tour the world again this March.
"We are so mad to play new songs, we get tired of playing the old songs, because it's like wearing the same dress and same pair of shoes every night when you go out, specially if you've got all these new shoes and dresses waiting to be worn.
"So yeah, we'll be playing new material, and we'll be playing the hits, but bringing some new life to the old songs too, giving them a lift, taking them somewhere else, why not?"
LOWDOWN
Who: Dolores O'Riordan, frontwoman for Irish pop-rock stars the Cranberries
What: New album Roses out now.
Where and when: Trusts Stadium, Henderson, March 15
-TimeOut
