Soft or hard? Alasdair Beal had a problem: two PCs running correctly installed copies of Microsoft Windows XP crashed often and at random. In such cases, I replied, it is always a hardware fault. But how could the same hardware fault afflict both a desktop and a notebook made by different manufacturers? Toshiba put the problem down to a loose processor fan and repaired the notebook, but when all the software was reinstalled, the problem returned. This time, Alasdair noticed that Paperport was open each time it crashed: "When Paperport was idle, just sitting there, the processor activity shot up to 100% and stayed there. This is onerous for processor cooling and I suspect it is what triggered overheating problems on both computers." The problem was solved by downloading the Service Pack for Paperport 8 from Scansoft's website. Now, processor activity falls to 0% when the program is idle. As Alasdair says, "When is a hardware fault not a hardware fault?"

Something that appears to happen with one version of Paperport could afflict other software, and I have seen AOL Instant Messenger 4.7 get stuck and "max out" the processor on my Windows 2000 machine. Alasdair may have found the answer to some otherwise inexplicable problems.

Spam victim
Spam email, including porn, is going out purportedly in my name, using my .com email address - I know this because such mail has been "returned" to me as undelivered. Can anything be done to stop this form of electronic impersonation? Andrew Bibby
www.andrewbibby.com

JS: The internet developed as an open, academic system and its openness is all too easy to abuse. There is nothing to stop spammers from forging From: and Reply To: addresses. The only thing you can do is make sure you are not contributing by running an open mail relay: see www.ordb.org/faq.

Internet service providers could help by closing or blacklisting open relays and by blocking mail with forged addresses. Unfortunately, this requires some effort and most cannot be bothered.

Back up If I want to back up my email, stored in Outlook Express, which files should I copy?
Martin Rosenbaum

JS: You should take backup copies of all the files in your mail directory, but particularly Inbox.dbx and Folders.dbx. You can find your mail files by selecting the C: drive, pressing F3, and putting *.dbx in the Search for files box. For further help, see Q270670 in the Microsoft Support Knowledge Base and the OE FAQ</a. If your mail is important, consider using Express Archiver, which is designed to do the job.

DIY
I was thinking of saving some money by building my own computer: can you suggest any publications or websites that might help? I know relatively little about the various components needed, or how to assemble them. Richard Atkinson

JS: I would like to see every schoolchild build his own PC, for educational reasons, and it is a good way for geeks to get exactly what they want. But it is not a good way to save money. Dell can buy components a lot cheaper than you, unless you resort to inferior parts that may be unreliable or not work well together. However, if you refuse to be discouraged, www.buildyourown.org.uk is a very useful site.

Not found
My laptop running Windows 95B suddenly has begun to throw up an error message on start-up: "A required .DLL file, ECOMWR.DLL was not found." The computer appears to function normally, except for shut down. Ought I be worried and, if so, what should I do about it? Mike Quigley

JS: You should always be worried if a file is not found: it could indicate virus activity or, all too often, anti-virus activity going wrong. In this case, it seems to be a bug in McAfee's virus scanner: search Google for Q319898 in the Microsoft Support Knowledge Base. To fix the problem, download the VirusScan 6.01.2000 upgrade patch from McAfee or the larger upgrade to version 6.02.

On trucking
My problem stems from installing an Ethernet card to allow broadband access. On start-up, I get a box saying: "Please insert your CD-Rom with the virtual truck program. Looking for file d:\installs\paceeth\vtruck.exe". I cannot locate it. Simon Barrow

JS: Broadjump Virtual Truck is the name of a cable modem installation program used by NTL, among others. Happily, your problem is covered on the troubleshooting page.

Backchat
· Last week, John Lee wanted his vanishing favicons - the little icons provided by some websites - back. Simon Aubury has found "a terrific tool called FavOrg. It scans the websites in your Favorites list for favicons and refreshes the icons if necessary". The program is free but you have to register with PC Magazine to download it.

· James Cheyne wanted to reach the UK version of the Financial Times's home page but, living in the US, was getting the American edition. Mike Turner and John Westbrooke have pointed us to the menu bar on the left side of the screen, which lists UK, US and Global. "Just click the one you want." See www.oed.com/public/news/images/doh.gif.

· Send your questions and comments to Jack.Schofield@theguardian.com
Published letters will be edited for brevity but please include full details with your original query