About a year ago I bought a new laptop with Windows 7 as its OS, and I gave the old one, which has Vista Home Premium, to my 8-year-old son. I created a separate account for him so that I could exercise 'parental control', but removed just about everything from my account--documents, programmes etc.

My son just uses the computer for games, but as they have seemed to be running very slowly of late, I just did a check for viruses, malware, software conflicts and so on. What I have discovered is that the hard disk, which has a capacity of about 70.2Gb is virtually full (68.8 Gb utilised) and there is only 1.46 Gb of free space. This seems unbelievable seeing as the programmes and games installed amount to a mere 20.1 Gb, and there is very little else on the PC.

I've tried defragmenting and disc cleaning, but I cannot really remove much else since the remaining software is Acer and Microsoft system files or flash players etc, necessary for the functioning of the games my son uses. Surely this shouldn't be necessary anyway if the software only occupies around 20 Gb.

Any ideas as to why the disk is virtually choc-a-block, and how I can put things right??