Windows 7: PSU question

my pc has recently been acting weird, i am thinking or hoping that it is the psu, sometimes the display and sound and functionality of the pc just go, black screen with nothing but the pc is still powered on and sometimes the display would just go to solid horizontal lines and i would have to force re-boot, i have lots of upgrades on my pc and lots uf usb devices. i have only got a 450 watt psu, i know i need more power. do you think these symptoms would be to do with a under powered system, i cannot find anything in the event log..

Hard to tell, but I wouldn't think so. Could also be your MB or CPU. What brand/model power supply? Have tyou changed any of the hardware recently?

Try adjusting your Screen Saver settings, power settings, advanced power settings.
Change put the computer to sleep to never.
Change Turn off hard disk after setting to never.