Plus: six free tools, a CMOS repair and an unfreezing trick.

This article appears in the November 06 issue of PC Advisor, onsale now in all good newsagents.

All too frequently, PCs seem to be troubled, in one way or another. A corrupt file, a bad application, or even a moribund CMOS battery can all cause grief. Read on for some PC therapy.

The Hassle My PC freezes periodically. How do I unfreeze it without losing my work?

The Fix In Task Manager, select the Processes tab, choose Explorer.exe, then End Process. Select File, New Task, type ‘explorer' and click ok.

The Hassle I can unfreeze my PC by following the above advice, but the lockups keep happening.

The Fix First, scrub your temporary and internet cache folders using CleanCache 3.0. Then run Windows' Check Disk utility.

Open My Computer, right-click the drive, select Properties, Tools, then hit the Check Now button under Error checking. Have 'Automatically fix file system errors' and 'Scan for and attempt recovery of bad sectors' selected. You should activate your PC's antispyware and antivirus tools, too.

If that doesn't work, try getting rid of damaged ActiveX programs. From Control Panel, choose Internet Options, General, Settings, View Objects. Right-click to delete any items marked ‘Damaged' in the Status column. You might have a corrupted file, so run System File Checker to verify and, if necessary, reinstall those files on your system. To do this click Start, Run, then type CMD. Type ‘sfc/scannow' and wait – the scan seems to take forever to complete.

If your PC is still having problems, they may be more deep-rooted and you'll need to work out which program or process is causing the freezing. Systernals has three superb diagnostic tools. FileMon gives a real-time view of every running program. Watch for a specific program's behaviour just before a freeze. RegMon does the same for the Registry, while Process Explorer takes a close look at Windows processes.

The Hassle My PC often boots to a black screen with a message saying my hard drive doesn't exist. But when I reboot, everything's fine.

The Fix You have a dying CMOS (complementary metal oxide semiconductor) battery on your motherboard – a common symptom is that your PC's clock reads the wrong time. You'll need to record the system's existing CMOS settings, which you can find in the PC Setup program. When you boot, you should see PC Setup access instructions before Windows starts. Record the details with a pencil and paper, or use a digital camera to get a snap of each page.

Alternatively, try Super Win's WinRescue. Get another battery from a hardware shop and then follow the steps outlined here.