Hi Nergal and hazelnut, thanks for the help.
My PC specs are:
OS: Windows 7 32 bit SP1
Processor: Intel Core2 Duo CPU E4500 @ 2.2GHz,
RAM: 3 GB
Graphics adapter: ATI Radeon HD 5400 Series
Browsers: I generally use Chrome (Version 34.0.1847.137 m) or IE (Version 11.0.9600.17107). I do also have Opera and Firefox installed, but never use them (I think my daughter uses Firefox in a different user account (on the same PC) occasionally).
Other security software (all has been running for several months): CryptoPrevent by FoolishIT (v. 4.3), Malware Bytes (v 2.0.1.1004), BitDefender Internet Security (Build 17.27.0.1146)
I'm running CCleaner within an Administrator account, although I still have UAC prompts enabled. I haven't tried running CCleaner as Administrator (that was my next thought in case the files it encountered were in use, but the fact that it hangs on different files after successfully running in Safe mode makes this thought a bit redundant I suspect?)
I started this CCleaner clean process around 20:55 tonight, and came back to it at approx 22:10, it was still at 0% and I had the same problem - unable to launch other apps / task manager or shut down, so had to power off with the button on the front. After a reboot all services appear to be working normally. I can't see how to attach the log file itself, so I've pasted the contents below, I took a photo of the screen showing CCleaner running with a 0% progress bar and the system clock showing 22:07, I can't work out how to attach that, but let me know if you want to see it (and tell me how to send it!):
Log file title: CCleaner_v4.13.4693_2014-05-20_20-45-17.log
[20:45:17::401][iNFO ] CCleaner v4.13.4693
[20:45:17::402][iNFO ] MS Windows 7 Home Premium 32-bit SP1
[20:45:17::402][iNFO ] Intel Core2 Duo CPU E4500 @ 2.20GHz
[20:45:17::402][iNFO ] 3.0GB RAM
[20:45:17::403][iNFO ] ATI Radeon HD 5400 Series
[20:45:17::404][iNFO ] Username: Jamie
[20:45:17::404][iNFO ] Application Started
[20:55:10::274][iNFO ] Entering Cleaning
[20:55:10::274][iNFO ] OnBegin
[20:55:10::274][iNFO ] OnRuleStarted | 3001 | 3101 | Temporary Internet Files
[20:55:10::586][DEBUG] C:\Users\Jamie\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.IE5\QQ7SG023\xperia250[1].png
[20:55:10::588][DEBUG] C:\Users\Jamie\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.IE5\HPJSJFJY\slot1[1].htm
[20:55:10::589][DEBUG] C:\Users\Jamie\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.IE5\WYRTT3Q7\slot4[1].htm
[20:55:10::793][DEBUG] C:\Users\Jamie\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.IE5\HPJSJFJY\mu123[1].png
[20:55:11::010][DEBUG] C:\Users\Jamie\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.IE5\HPJSJFJY\pccompanion_promotionarea[1].xml
[20:55:11::342][DEBUG] C:\Users\Jamie\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.IE5\QQ7SG023\care123[1].png
[20:55:11::557][DEBUG] C:\Users\Jamie\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.IE5\N3PZD7DR\campaigns[2].js
[20:55:11::785][DEBUG] C:\Users\Jamie\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.IE5\N3PZD7DR\PCCompanionDatabase[1].xml
[20:55:12::051][DEBUG] C:\Users\Jamie\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.IE5\N3PZD7DR\xperia123[1].png
[20:55:12::302][DEBUG] C:\Users\Jamie\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.IE5\QQ7SG023\base[1].css
[20:55:12::304][DEBUG] C:\Users\Jamie\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.IE5\HPJSJFJY\slot3[1].htm
[20:55:12::594][DEBUG] C:\Users\Jamie\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.IE5\WYRTT3Q7\MandatoryUpdates[1].xml
[20:55:12::598][DEBUG] C:\Users\Jamie\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.IE5\QQ7SG023\slot2[1].htm
[20:55:12::818][DEBUG] C:\Users\Jamie\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.IE5\WYRTT3Q7\vu250[1].png
[20:55:13::035][DEBUG] C:\Users\Jamie\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.IE5\N3PZD7DR\DriversDatabase[1].xml
[20:55:13::412][DEBUG] C:\Users\Jamie\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.IE5\WYRTT3Q7\ScriptsDatabase[1].xml
[20:55:13::569][DEBUG] C:\Users\Jamie\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.IE5\WYRTT3Q7\errorPageStrings[1]
[20:55:13::835][DEBUG] C:\Users\Jamie\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.IE5\WYRTT3Q7\background_gradient[1]
[20:55:14::028][DEBUG] C:\Users\Jamie\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.IE5\N3PZD7DR\unknownprotocol[1]
[20:55:14::195][DEBUG] C:\Users\Jamie\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.IE5\HPJSJFJY\ErrorPageTemplate[1]
[20:55:14::468][DEBUG] C:\Users\Jamie\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.IE5\HPJSJFJY\bullet[1]
[20:55:14::676][DEBUG] C:\Users\Jamie\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.IE5\N3PZD7DR\httpErrorPagesScripts[1]
[20:55:14::870][DEBUG] C:\Users\Jamie\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.IE5\HPJSJFJY\info_48[1]
[20:55:15::287][DEBUG] C:\Users\Jamie\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.IE5\HPJSJFJY\bdav_winxp_winvista_win7_programfilesfolder.exe[1].md5
Thanks again,
Jamie