As some of the internet's biggest names have discovered to their cost, success has its dangers. Latest to be enrolled to this school of hard knocks is online bookseller BOL.com which last week offered 20,000 free books , during one hour of a weekday afternoon. It wanted attention and got it, if partly for the wrong reasons.

Netizens love something free and flocked to the site. But those who got in reported snail's-pace progress, and frustration as they tried to place an order. Others didn't get in at all, seeing only a collection of error messages.

As IT newsletter Need to Know acidly pointed out: "The pain of thousands of new users being introduced to BOL via the 404 page [an error message] certainly made a splash." NTK's coverage at www.ntk.net/boldoh shows a perfect example of a PR stunt gone horribly wrong.

To be fair to BOL, its site appears fast and stable under normal conditions. The same cannot be said for US site eBay, which last weekend suffered two more outages lasting a total of 21 hours.

It is the latest in a series of serious faults to hit the online auctioneer. With a recent crash thought to have cost it up to $5m in revenue, the problems are hardly helping stabilise its yo-yoing stock price.

But as Hotmail and AOL - two companies who have both had reliability problems - will testify, the long-term harm that crashes cause to an online reputation is much, much harder to put right.

Online gadgets, giveaways and PR stunts might be the glamorous side of internet marketing, but perhaps dull old-fashioned reliability matters more to surfers already irritated by the world wide wait.