For the past three months I have had a number of niggling problems with my Pentium 200. It was assembled for me by a shop in the 298 Computer Mall and worked fine for the first few months. When I discovered my hard disk was getting full, I removed some programs that came with the computer which I was not using. The PC started developing problems - sometimes my modem refuses to work, while at other times it is my printer. Later, Microsoft Word started developing errors at launch time, though I can still work by 'ignoring' the problem. Also, Microsoft Internet Explorer works erratically. The staff at the shop I bought it from told me it probably was a virus, but they have not been helpful. Have you any advice? JOHN STEIN Sheung Wan My advice is rather general, given what you have told me about your computer. Nevertheless, it applies to most PC users. PCs running Windows are not like Macs where you can get rid of software by trashing the entire program. There are all manner of files associated with applications that embed themselves in your system configuration and operating files, and software has to be 'uninstalled' carefully to avert problems from developing. You can use the Add/Remove Programs function in Windows 95's Control Panel. Many programs come with their own uninstall functions built in, and it is recommended you use them first. If you have deleted entire applications, you definitely have left bits lying around your system that will cause problems somewhere. Programs like Norton Utilities (especially Norton Disk Doctor) are good at going through your system, locating problem areas and fixing them with or without your prior authorisation. That aside, your computer shop may be spot on about a virus. I assume you have an anti-virus program on your computer (unless it was one of the programs you deleted). Programs like F-Prot, Norton Anti Virus, McAffee and several others can protect your computer from viruses transmitted by disk or off Internet downloads. They are all useless unless they are kept up-to-date. New viruses are born almost by the hour, and the anti-virus companies make a valiant effort to stay on top of them. They regularly send out (or allow you to download) updates to your virus database. You should update your virus database at least once a month to be totally secure. Most viruses will not knock the socks off your computer outright, but will hang around your hard disk causing a great deal of inconvenience, with symptoms similar to those you describe. Apart from running utilities and virus cleansers on your system regularly, here are a few other ways to ensure a healthy computer system: If you are not sure about what you are doing, do not mess about with your system. Most importantly, do not poke around its insides. I have a friend who has about five computers at home which do not work because he tried to fix various problems by taking them to pieces himself. I have learned more about what not to do to computers from him than anyone else. Do not attempt to reformat your hard disk straight away. Reformatting your disk may be the solution, but at least wait until you have the drivers for your peripherals so they can be installed after the reformat. Often people try to re-install Windows 95 from a CD-Rom (the common media for most software these days) after a reformat but discover their CD-Rom does not work because the drivers were erased during the reformat. This is especially a problem for users such as you, whose computers were built to order and did not come with a full manual and set of drivers. Check the power supplies of any new peripherals you buy, particularly from unauthorised dealers. They usually are parallel imports, and though parallel importers help keep prices affordable, they do not always sell you equipment built for Hong Kong. Plug a device built for the US into a Hong Kong power socket without the right adapter and you will see molten plastic form into interesting shapes. Think carefully about any new software you might want to install. I strongly advise you install only what you are sure you will use, or you might have to remove it later and this is a pain. Remember - treat a computer with respect and it will serve you well. E-mail Larry Campbell at firstname.lastname@example.org or write c/o Technology Post, 28th floor, Dorset House, Taikoo Place, 979 King's Road, Quarry Bay. Fax 2565 1624.