Is this an IT-managed computer? If not, it's quite possible that a third party software has changed permissions on your system. I did a quick search for the error message, and it looks like there are a couple of possible fixes that you might want to try.
Thank you Elaine for taking your time to look into this problem and replying me. With regards to your reply, the PC isnt it-managed and I'd really be glad and grateful if you tell me what I need to do to fix this problem. I anticipate your benevolent feedback.