Fixing a PC that shuts off by itself

Q: My desktop PC has started turning itself off less than five minutes after I turn it on. But when I restart the PC, it stays on with no problem. I run anti-malware software daily. What's wrong?

Maggie Freese, Plymouth

A: If your PC has an electrical short circuit that's causing it to shut off, fixing it will be a job for a repair shop. But first check on three things you can correct yourself.

• Look on the back of your computer and make sure the voltage selector switch is set to the U.S. standard of 110 to 115 volts. A higher setting could cause your PC to turn itself off.

• Check for a malfunctioning surge protector that could interfere with the PC's power. If you plug your PC into a power strip that contains a surge protector, try plugging the PC directly into the wall outlet instead. If that solves the problem, buy a new power strip/surge protector.

• Place your hand over the cooling fan vent on the back of the PC to see whether the fan is running. If it is, buy a can of compressed air and (with the PC turned off) blow it into the fan vent to dislodge any dust that might be blocking the vent and causing the PC to overheat. (PC's are designed to shut down if they overheat; that avoids damage to computer components.)

If the cooling fan isn't running when the PC is performing a task, take the computer to a repair shop to see whether the fan and its attached power supply unit need to be replaced. (Don't replace that equipment yourself because you could receive a powerful electric shock.)

Q: When I used Microsoft Office 2003 on a Windows 7 PC, I created many Word document and Excel spreadsheet files in the .DOC and .XLS file formats.

When I upgraded to Windows 10, I switched to Office 2007 and created more files. But I didn't like Office 2007, and went back to using Office 2003. Now I can't open any of my Word or Excel files — I just get blank pages. What can I do?

Roy Larson, Chaska

A: Unfortunately, Office 2007 has converted your Word and Excel files to a new format that can't be read by the older Office 2003.

Beginning with Office 2007, Microsoft introduced a new default file type for Word files (they use the .DOCX suffix instead of the traditional .DOC) and Excel files (they use the .XLSX suffix instead of the former .XLS).

In addition, I suspect that each time you used Office 2007 to call up an old document or spreadsheet, it was stored in the new file format.

Here are three solutions:

• Install an Office 2003 update so it can read Office 2007 files (see tinyurl.com/ybpuufck).

• Resume using Office 2007 because it can read your files in their new format.

• Use for-pay file-conversion services such as Zamzar (tinyurl.com/pdaumrr) or Convertio (tinyurl.com/yazytz7s) to convert your Office 2007 files to Office 2003 files.