Why does my Clio cut out ?

Occasionally, when I leave work at the end of the day. I can start my automatic 1600 Clio, but when I take my foot off the accelerator to transfer it to the brake to put her in drive or reverse, the engine dies ! I have to sit there for 10 minutes, with my foot on the gas keeping her ticking over untill she warms up enough that she'll keep going when I remove it ! She doesn't do it often, and has not played up, even when covered in snow. Please, HELP ! :-(