No screen, 2 rounds of 1long beep+3 short beeps; doing for a while

I have been having a problem with my Toshiba Satellite laptop - since about mid July '07. I will start up the machine and get the 1-long beep + 3-short beeps (standard AMI BIOS memory error). I've pulled the 512 MB DDR Memory card reseated and/or switched sockets. Sometimes is works - other times not. The 'solution' is a number of hard shut-downs and finally I get a screen.

I read the report filed by dugihowsa on posted on Sep 13, 2006 - saying the problem was a video problem. This made sense, because the problem was first noticed the morning after I used the laptop for a conference in which the display was set to work with an LCD projector. I have tried to reset that to DEFAULT - but am not sure I was able to do so successfully. But, that was the origin of the problem.

I applied the 'solution' offered and - for a while it seemed to be the answer.

The problem has become more than annoying. I spend a lot of time just trying to get the computer to work. I'm writing this from an alternate desktop.

Is there a way to tell if the RAM Chip is bad or if it's the MotherBoard without going through costly diagnostics or part trials?

I'm getting ready to engage the full treatment (including wiping the JRE's) and applying the steps offered.

I hope this works. Or someone can offer me THE CORRECT solution. Other than buying a new laptop. ". >

Thanks ... les