My Mac will not start. When I hit the 'On' button, the machine makes a funny sound, my screensaver comes up then nothing happens. I can see in the upper-right-hand corner the magnifying glass that forms part of the menu bar. But when I move the cursor there, the so-called 'beach ball of death' appears. What can I do? Name and address supplied DQ: There are few problems as frustrating as a personal computer that will not start. This sort of problem will happen to a Mac, just like any other computer, at some stage. There are things you can do to protect yourself: back up all your important data is one. But you ought to back up the entire system. A great site for Mac users is www.creativetechs . com/iq/my_mac_wont_start.html, which has what I consider an essential reference section. It contains a little portable document format file that is called, appropriately, MyMacWontStart-PocketMod.pdf. This file has several last-resort ideas to try before you take the machine in for repairs. It has saved many Macs. The first thing you need to do is boot the machine with the 'Shift' key held down. You will get a message that says 'safe boot'. Ignore the message and wait. It can take a long time for the machine to boot this way, so don't panic. Once the machine comes back to life, simply shut it down as normal then reboot it without holding down the Shift key. That process will often solve the problem. If that does not work, you might have a more serious issue. Look at the guide and try the series of possible fixes. If none of them works, take the machine back to Apple. Update: In response to a query (Post Magazine, July 15) about charging multiple incompatible devices, several readers pointed out there are a few products available that can perform this task. Thanks to Mukesh Balani and Lester Lim for their suggestions. One of the most promising solutions comes from WildCharge ( www.wildcharge.com ), a company based in Scottsdale, Arizona. The company sells its products over the internet and mentions support for Apple's iPod nano and Motorola's Razr mobile phone. Its site does not mention if the company's charger product can handle 240 volts. My advice would be to wait until WildCharge devices are sold in Hong Kong. In the interim, the ChargePod (above; callpod.com/products/chargepod) could be what you want. It may not have the most elegant design but it can charge up to six devices with one power cord - including a personal digital assistant, MP3 player, mobile phone and Bluetooth headset. You will need to get a Chargepod adapter (there are 33) for each device you have. Be careful: many of the adapters are labelled 'out of stock'.