Yeah I have the same problem . It started when I installed a cordless keyboard and mouse. I'm sure there's a way round it but I haven't bothered to pursue it. I turn the PC on first thing in morning and off last thing at night!!
With todays monitors screensavers are mostly for show as the problem of pixels being burnt onto the screen surface does not happen so you can leave your monitor/computer on for long periods with no adverse reactions so I would imagine leaving the monitor on using a screensaver would be ok.