Hot Tosh
I have a Toshiba Satellite laptop. The recent hot spell has seen it turning itself off after about 30 minutes, although I can hear the fan working. Adam Forrester

Jack Schofield replies: Which processor? Fast desktop chips can cause overheating in confined notebook cases, as Online warned in March last year. At the time, Toshiba's marketing manager told me: "You run the risk of overheating and thermal shutdown in a bad design. But you can design around the fact that you are using a desktop processor and keep the chip within Intel's guidelines." In August, US users launched a class action against Toshiba America, alleging that some models of the Satellite 5005-S504 and 5005-S507 had a design flaw that caused them to overheat and shut down.

Toshiba UK says not to use your notebook in direct sunlight or block the machine's ventilation. It can arrange to check your PC for component failure but there could be a fee if it is not under warranty. Call 0870-4448944.

Many notebook PCs that do not have power-saving Pentium M or Centrino chips may be operating at high temperatures. You can help to keep them cool by propping them up to increase air circulation or aiming an external fan at their bottoms. Bytecc offers two stands www.hardcoreware.net/reviews/review-75-1.htm and www.byteccusa.com/product/cooler/TDD-3000.htm, and there's also the Lapworks Laptop Desk Notebook Cooler & Tray Stand. It might be hard to buy one in the UK, but it would be easy to make something similar.

Tilde invader
A curious file has taken to appearing and reappearing on my desktop. It has the name "~", and its presence is indicated by a plain Windows icon. Stephen Mennell

JS: It's harmless. It is the result of installing the April 2003, Cumulative Patch for Outlook Express (330994). The temp file appears after a change is made to your address book in Outlook Express. The Address Book (.wab) is being updated correctly, but it seems that Windows' scratch copy (.wa~) throws a tilde on to the desktop. You could uninstall the patch, but I think your best bet is to ignore it and wait for Microsoft to acknowledge and then fix the glitch. See www.microsoft.com/windows/ie/downloads/critical/330994. Surprisingly, this was the week's most common query, and the first for many moons to surpass "How do I block these Windows messenger pop-ups?"

Dust it
I had problems with my computer and decided to start again by using the system restore CD. However, about 22% of the way through the installation, a critical error message came up saying 0x0B read fault. Dot McDowell

JS: The PC has failed to read the CD, either because the CD is damaged or dirty or, more likely, there is fluff or dust on the CD's laser read head. You could blow it clean, eg with compressed air, or try a CD drive cleaning kit. If all else fails, it should be easy to slot in a new drive, if the case is a standard design.

Hijack!
My Internet Explorer browser has been hijacked by the website i-lookup.com. A toolbar keeps reappearing despite me continually turning it off. A dialler program also keeps popping up etc etc. Mike Powell

JS: The i-lookup website offers an uninstall.exe file to remove its browser hijackerwww.i-lookup.com/faq.php, but both Spybot Search & Destroy and Ad-aware 6 should be able to get rid of it. I suggest you read the Browser Hijacking page at SpywareInfo . This has links to several popular scumware removal tools, including Hijack.

Backchat

· John Whitehead wanted to upgrade the 400MHz AMD processor in his PC to run Windows XP. Mohamed Sobhy says: "I have recently installed XP Pro on a computer with a 300MHz Pentium II and it works fine. The important thing is to have enough memory, as you mentioned. At least 256MB are needed, as XP Pro needs close to 200MB to run at full speed. With older motherboards, the correct RAM must be used. Crucial is an excellent place to get any type of memory one needs within 24 hours."

· Jo Duddy wanted to use Polish characters on her iMac, and I pointed her towards the Central European character set. Jurek Narozanski says: "there is perhaps one website that you have omitted, which could help Jo Duddy above all others: Apple Polonizacja and its download page. Unfortunately, it is in Polish language only, but it contains everything for Polish CE fonts for OS 9 through to OS X v10.2.4. It also gives the two key-board simulations, maszynista and programista. The latter is far superior for use on UK keyboards. I use it on a daily basis."