Something strange has happened. Somehow I've downloaded and installed what appears to be a free version of AVG Ant-virus 2012. It was late at night and I was tired but I think it was when I clicked on your link to CCleaner. I only realised it was the wrong software when I looked at your instructions and they didn't match what I was seeing. File I downloaded was "avg_avct_stb_all_2012_2178_ppc2.exe". Did something on my computer re-direct your link to a bogus site and I've now installed a malicious application?
If it is bogus, it tells me that the original exe file I downloaded which started this conversation is infected with a Trojan Horse: Generic28.BGTD.
PC appears to be running OK but I am paranoid that I've installed something (rootkit?) that might be monitoring my sessions, keystrokes, passwords etc.