Acer Aspire 5315 screen question.

Hi, As per the title, I have a 5315 with a screen anomaly. I was given a virtually unused 5315, it had been lying in a cupboard for virtually all its life. It was running Vista with a password so I installed Win7 and after playing with it realised it was a bit slow.
Checked on here and read through the applicable threads re upgrade etc and eventually set on a T7500 and more ram. I also replaced the Thermal tape with a copper shim ( cannot see any difference, although the fans are very quiet and never go into high mode ) and replaced the Wireless card with an Intel 4965 AGN.
I have just this day installed Vista Basic using the COA from the underside of the comp. This is when the screen question arose. During the install as per usual the screen is Black for quite some time and during this period and only when Black I noticed the background had Blue outlined shapes with Black filling much like when water has not been wiped up correctly and leaves odd shapes on a surface. I initially thought the screen was dirty even though it was spotless. Once the Black screen disappears the screen is perfect.
I would appreciate any thoughts.
regards,
Eddie.
I would like to say thank you for the effort and time that the people who did all the work on the 5315 upgrade thread. I read most of them and am amazed at the numerous same questions that kept being asked.