I have a Dell D620 that is giving me fits. It displays a program I am working on and then suddenly the screen is full of stationary and multicolored vertical lines. This happened in the past but I could usually fix it by just rebooting but lately it is almost constant. I have performed the following actions and observations in an attempt to diagnose the problem:
1. Hooked up an external monitor and it works with no problem.
2. Replaced the inverter with no visible difference.
3. The illumination for the screen is always on and is not dark
4. Periodically and randomly I get a normal screen that lasts sometimes for several hours or until I turn the machine off.
5. The bios and all system drivers are current.
6. When the screen is normal I can access all programs along with having full access to Intranet and Internet resources.
7. No error codes are generated by the system when the display goes bonkers.
I would appreciate any and all help to resolve this.