Thanks for the speedy reply. I found the advanced tab and have tried your suggestion to 'Show detailed information on action performed' but that simply lists up every file it's checking (a nice feature nonetheless).
I have now started played around with the default settings (I had not actually 'changed the settings without knowing what I was doing' as you surmised) and nothing, including pausing or terminating the the Standard Shield makes a difference - that tested, I have now reverted to 'Normal'.
The troubleshooting is of no use either (and don't forget Radlinker can be used for any type of program not just games - I created one for Notepad to test); I suspect that the tick regarding pop-ups is to prevent that annoying problem caused by desktop popups switiching the focus from a fullscreen program, ie game, that you might be running. The log shows no entries. I've scanned the Radlink and Radclock exe's and dll's just in case. In my ignorance I tried running the exe's and I don't get a warning (nothing else happens but I guess that's what you'd expect from such a utility). I tried adding the RADLNK extension to the list in the Advanced tab for the standard shield provider (but to no avail).
So to recap. I use Radlink to create custom shortcuts that include information for overclocking my GFX card but these shortcuts now will not run now I've uninstalled PC-cillen and gone over to Avast and I get an 'Access is denied' warning box whatever custome Radlink shortcut I try to run . Running the program with a standard shortcut is fine.