It seems that Windows has stopped recognizing the digital signature certificates of any application on my computer.
The digital signature certificates can however be viewed by right-clicking any signed application installer then selecting 'Properties' and clicking the 'Digital Signatures' tab.
However, when these installers are run--they display 'Unknown Publisher' for the 'Publisher' item. This causes issues with other applications that download and install updates, they usually exit with an "files not signed" error.
I have earlier stopped some of the 'Windows Services' through the 'Administrative Tools' section. However, not sure which service is to be restarted to get the digital signature certificates working again.
Please inform about what needs to be changed?