Hello ident and Andavari and sorry about the late reply but I was away. Yes ident, I know what you mean and thank you for the additional information. I thought from the start that the problem was caused by the registry and that something got corrupted. Obviously CCleaner can't write on the registry any more and the fact that the options do not stay checked clearly reflects it (they do not stay checked because the value cannot be written on the registry hive). Yes, XP is not supported any longer but CCleaner is still compatible with XP, as Andavari has pointed out, and in fact it works perfectly on my other Windows XP machine. Unfortunately we all know very well that no installation is identical to another, even if the configuration is exactly the same. I thought this could have been a generic problem that maybe had a working solution available but it is now clear that it is specific to my computer. I am convinced that something went wrong when I updated CCleaner. I tried the corrupt recycle bin fix that you suggested Andavari but it didn't work, thank you for suggesting it.
This is not a major problem anyway, just a minor annoyance and also everything else works fine on that machine so I am not going to troubleshoot this any further. I added the AUTO instruction to the CCleaner icon (CCleaner.exe" /AUTO) and as a work around it is very effective, basically offering the same functionality of the Run CCleaner Recycle Bin option.
Thank you very much for your help.