some time ago we migrated from pscan.eu to pscan.uk and that meant a new version of pscanloader.
If you have the old pscan.eu one then it will attempt to update to the new one, but sometimes the processes clash, and the way around that is to reboot the PC and try again.
If that doesn't work that just start a new installation in a new folder and basically just start again from fresh by following these instructions http://pscan.uk/install/install.html
Please report back if this works or not.