The spread of the 'I love You' computer virus in May caused chaos worldwide, but it has been beaten to the number one spot this Christmas by old favourite Kakworm.According to anti-virus vendor Sophos, 17 per cent of all calls to its helpline over the last 12 months have been about the visual basic script (VBS) worm which attacks Microsoft Outlook users. "Love Bug was a shooting star - lots of action and noise and fury for a relatively short time," said Graham Cluely, senior technology consultant at Sophos. "Meanwhile, Kakworm has crept stealthily to the top of the charts." The annual list shows the destructive power of script viruses such as I Love You and Kakworm which only account for 6 per cent of malware in circulation, but cause over a third of the total infections. The UK-based vendor was also surprised by the speed at which Christmas virus Navidad rose into the charts. Only discovered last month, the internet worm was made seventh place in the annual list with 3.4 per cent of calls.