Un-responsive Touchsceen

[Stgtech]

Hey all. I just purchased a 2001 LS-430 several days ago. Among several other things the touchscreen seemed tempermental and not responding while at the dealers and he promised to have it fixed. While the paper work was being taken care of, the car went in for the touchscreen and a few other interior issues. When we left later that day it was functioning great. He said all they had to do was "reset" it. Everything was fine for the remainder of that day and the next when i started it up late afternoon. However, the third day the touchscreen was completely unresponsive as before. The "I Accept" button is "untouchable". I managed to discover that by getting to the audio screen, anywhere you touched the screen activated the lower left corner, and would allow me to goto <sound>. Once there i could lower the bottom -most button (bass down.) No matter where on the screen i touched that was the only button recognized. I took it back to the dealer and they spent 2 days with it, believed it to be fixed, and called me. The car had been parked outside for several hours and when i got into it the touchscreen was again unresponsive. After about 10 minutes it became fully functional though. After the car was shut off however it was back to square one. Lexus has suggested i drive it for a few days and make a log of when its working and not and conditions to help thier technicians. I left and it did not regain function for nearly 30 minutes this time. Once again the car was turned off however it was dark and cool out. When the car was turned on it no longer responded. i made another 40 minute trip and it did not come back that time. that was tonight. I originally assumed it was sun/heat however now it apprears to be whenever the car is turned off no matter the time. It loads fine but i cannot get past the Accept sceen. I also noticed (and didnt think possible) that it appeared to regain functionality gradually across the screen from left to right. I felt i coudn't hurt to do a little research on my own. Sorry for this being so long but i wanted to include as many details as possible.

Thanks for any help you may provide. Aaron