Brian Jackson - Fotolia
IT directors across the UK this week breathed a sigh of relief after the first few days of the millennium passed with little lasting disruption from the year 2000 problem.
It was business as usual for most organisations on 4 January, with IT directors reporting minor bug problems as the date rolled over to 2000.
However, analysts warned against complacency. They said the worst could be yet to come, when most organisations return to work for the first time this week with several key dates still to be overcome.
"The peak of the Y2K problems will be in April, just after the first quarter accounts are done," said Karl Feilder, head of Greenwich Mean Time.
IT directors' celebrations this week were also tempered by claims that the millennium bug was little more than hype.
Some academics and business commentators have begun questioning whether it was necessary for the UK to spend billions of pounds on Y2K, when it had had so little impact.
"I am really annoyed by all this questioning of whether we needed to do it. There is no question that our systems would not operate if we had not invested the time and money," said Keith Bogg, divisional IT director at Marks & Spencer.
"Success should be measured by the fact that very little happened," said Roger Marshall, year 2000 co-ordinator of local government IT managers body Socitm.
As Computer Weekly went to press, the Government reported that any minor Y2K bug problems that were discovered over the date change had been dealt with.
The London Stock Exchange said weekend checks had gone well and no testing was needed on Monday. The Bank of England said that only minor glitches had been reported by some financial institutions.
Computer services company ICL received reports of eight possible minor Y2K issues from its 22,000 UK customers.
Fears that firms could be swamped by millennium viruses also proved premature. Because the viruses were so badly written they were unlikely to cause problems.
Hackers did, however, manage to break into some Web sites. The UK sites affected included Railtrack's national timetable, Lloyd's of London, Dudley Council, Cardiff County Council, the London Fire Brigade and Wyvern Business Systems.
Forthcoming danger dates
6 January 2000: first possible weekday mistaken for weekend day
7 January 2000: first weekly payday
29 February 2000: is leap year accounted for?
3 April 2000: first business day after quarter end 31 March 2000
31 December 2000: 366th day of the year 2000 - a potential problem for systems that use Short Julian days
1 January 2001: first day in 21st century
Y2K problems around the world
Pyongchon, South Korea: heat goes out in an apartment block for 900 families
Ishikawa, Japan: nuclear power system monitoring radiation levels fails
Tokyo, Japan: brokerages report glitches in record-keeping systems
Uppsala, Sweden: electrocardiograph machines stop working
Copenhagen, Denmark: glitch in Unidanmark bank's payment and information system
Washington, US: ground system processing satellite data fails
Various sites, UK: small businesses hit by failure of Racal-HSBC credit card terminals.