I have an intermittent startup problem. Sometimes the system tray doesn't fill up during startup, and the PC runs sluggishly, or doesn't open Internet Explorer, and other programs. If I try 'start, shut down' it hangs, and I have to cold reboot it. This usually solves the problem, but sometimes I have to reboot twice. I have Windows Defender and AVG Free, both up to date and I've scanned for viruses and spyware. I also have Registry Mechanic. It's a 2004 Holly PC with Chaintech Zenith 9CJS motherboard, Pentium 4 2.6GHz processor, Gainward nVidia 5600 Ultra 256MB graphics card and 512MB DRR400 RAM running XP Home. Any suggestions?