inc 2 reloads after exiting programs

[TheGlatMachine]

Lately, it seems like every time i exit a program by clicking the back arrow or home button, I get the HTC screen (white screen with green HTC in the middle), followed by Loading and then everything loads (as though i was powering on the phone). I have no idea what is causing this, or more importantly, how to fix it. It's not a full restart, but it really slows everything down. Any ideas what might be going on? My phone is almost two years old. It happens with almost every app, but not regularly. Any help would be great!

Thanks!