The US Patent and Trademark Office is continuing to complicate, confuse and condemn technology markets with the approval of two patents for Network Associates - one for "cleaning a computer" and another for filtering packets on a wireless network.

Patent 6,671,812, "Computer cleaning system, method and computer program product", covers McAfee's QuickClean software that removes unwanted data and software from a PC.

And patent 6,693,888, "Method and apparatus for filtering that specifies the types of frames to be captured and to be displayed for an IEEE802.11 wireless LAN", covers the monitoring of wireless data to ensure that it comes from a known and/or trusted source.

However, as with numerous other patents passed by the USPTO recently, both patents appear to give rights over basic approaches to technology that have been around for years and are widely used by a number of different companies.

Only last week, another new granted patent appeared to hand the entire anti-spam market to small player Postini. Patent 6,650,890 covered the pre-processing of e-mail and was laughingly dismissed by lawyer and competitors as impossible to impose.

However, patents are a very real threat. There is the ongoing dispute between Eolas and Microsoft in which the company was originally awarded $521 million because Microsoft had infringed its awarded patent for embedding interactive elements into Web pages. That case - disputed by Tim Berners-Lee is still ongoing, mostly recently being dismissed on appeal.

Symantec paid $62.5 million to small software company Hilgraeve for infringing its virus scanning patent in August last year. And Intel has just agreed payment of $225 million to Intergraph for infringing patents on parallel-computing technology.

Only last week, Hewlett-Packard made its first foray into suing competitors for infringing patents by claiming Gateway had not paid it for, among others things, inch-thick laptop computers, computer cursors and power management.

And then of course there is and was the ongoing discussions in Europe over whether to go the US and Japanese routes and open up software to patenting - something that many people fear will sound the deathknell for the open source movement.

The reason for the sudden glut of questionable patents is the time delay from when the US patenting system was opened up and the length of time for the USPTO approval system. We can expect more, and with each one, a slight undermining of the protective patenting system.