Dropping Frames, Out of Memory

I'm having issues with a current project. When I play unrendered media (green bar) I begin to drop frames and the issue continues with media that does not need to be rendered. I also get the "out of memory" warning when I try to render.The strange thing is the the dropping of the frames is not consistant and seem to get worst as the day goes on. I thought the Mercury Elite-AL Pro FW800 drive was the issue because it was formatted Mac OS Extended (Journaled). The project is about 35MB's ,with a lot of sequences and large scanned 300dpi images and up to 4 video layers. I made a smaller project with smaller images and 2 video layers. Still same issue.

I transfered the media from the FW 800 drive to my 4TB Sata drive and reformatted the FW800 to Mac OS Extended, but the same issue was present. I then played the project from my 4TB Sata drive the issue was present. My client has his own FW800 drive and his project plays back fine. I had him bring his drive to me and we swapped drives. I still had the same issue and his computer played back the project fine. I opened an old project on an older G-Raid FW800 drive and didn't have an issue. I placed a up to 5 video layers with filters to produce a green bar and still didn't have an issue?

Does anyone have an idea? I have 4GB of RAM. I use to have 8GB, but a stick went bad so I had to remove 4GB's. Can it be related to RAM? Perhaps a conflict with a filter?

Best,

Martin