It may be viruses or it could be that your primary display driver needs to be reinstalled/updated... Safe Mode uses a basic vga driver that is encoded in the bios chip, safe from the rest of the system, which could be why it works in safe mode.... It could also be a service and/or program causing it.....While you're in Safe Mode, only the minimal set of drivers and services required to run Windows is loaded. This helps minimize loading viruses and/or other fluff software, so if a virus is the problem, Safe Mode has obviously subdued it/them..
Start by going into Safe Mode again, click START, Click RUN, type: msconfig
and click "OK"
Go to the SERVICES tab, check the box that says, "hide all microsoft services", click on "disable all", click apply, click ok, restart the computer and let it go back to normal mode to see if the situation has improved.. If not, go back to safe mode and instead of clicking on the "services" tab, click on the "start up" tab, then click on "disable all", click "apply" , click "ok", restart and go back to normal mode to see if the problem is corrected... If either one of these suggestions helps, then you'll have to turn services and programs on/off to determine which one is causing it... If none of these work, go to the Malware forum here at CH post in there... read the pre-posting instructions for beginning malware removal... If the problem isn't malware, then we can try reinstalling the display driver...