When trying to download and install new programmes and updates onto windows
recently, I have been having problems when it comes to installing the newly
downloaded files. On different occasions, it has come up with
"error1500","error1607","error1618" and with the general message of "windows
installer service could not be accessed" or "another installation is in
progress". This occurs after download of file when the installation process
is beggining. It tells me to "close all other installations", but there are
no other apparent installations running.

I have looked at online advice which just tells me to restart my computer,
which i have tried on many occasions and which fails to help.
Today, I was trying to install an antivirus application which actually told
me it could be because either I am "running windows in safe mode" or "the
installer is not correctly installed".
Could someone please send me in the right direction in checking if these are
indeed the causes, or if i need to look elsewhere.
Your help would be appreciated greatly,
thank you