Windows and Icons "melting"

I'm running XP Home Edition. Have: AVG Free, Spybot Search and Destroy, SpywareBlaster, AdAware SE Personal (Lavasoft) and Windows Defender. My ISP is Juno 8.0 and have had it for a few years now. Have an E-Machine E-Monster 500a for 5 years now and love it. I scan once or twice a week and I'm always up to date with MS security updates. What started a few weeks ago is that my icons and desktop picture start to disappear from the top down but do come back. Don't know what you call it so I came up with "melting". This happens when I click on the Juno icon to log on. Sometimes it happens to a window or two while on-line. Doesn't happen all the time, just once in a while. Can anybody tell me what could be causing this to happen and how to fix it? Thank you. By the way, you guys forgot my birthday. I'm 53 today.