Thanks SYL\X/3K and Grievearz
Actually I've already done a complete clean install of my Vista Ultimate OS. I'm just about to do a reboot before I reinstall any of my software programs to see if the problem is resolved. If the reboot goes smoothly at this stage I'll begin to reinstall software doing a reboot after every individual installation to see if the problem is indeed being caused by a particular program. If my initial reboot proves to be problematic I'll promptly return here to inform you of it. Otherwise if I do find that it is one of the software applications I will also inform you of which one it is for future reference. Of course if the problem has been resolved due to the reinstallation of my OS you'll be informed of this as well. Wish me luck...!!
Cheers
conductor